bitcache: added safeguard condition before calling Bitcache_FileRepository::rmdir_rf() method, #370433 by bjraines

Ensure that file system repositories are created when invoked from hook_enable() in dependent modules (patch by miglius).

- #433708: Implemented support for tokenized file system repository paths.
- Added an optional repository parameter to the Services API method 'bitcache.put'.

- Implemented hook_form_alter() to display a warning on the Global Redirect settings page in case the 'Deslash' option is enabled.
- Added a new database table, {bitcache_index}, for keeping track of which repositories have which bitstreams.
- Added schema update #6005 for creating the {bitcache_index} table.
- Added schema update #6006 for populating the {bitcache_index} table.
- Implemented index updates on bitstream creation and deletion.
- Ensured the absence of a superfluous language prefix for the URLs returned by bitcache_resolve_id() and bitcache_l().

- Added a new API function bitcache_id_file() to replace the direct usage of sha1_file().
- Replaced usage of sha1() and sha1_file() with bitcache_id() and bitcache_id_file().
- Imported a dummy backend for use as a template for implementing storage adapters.
- Implemented an Amazon S3 storage adapter using the Tarzan library <http://tarzan-aws.com/>.

#400106: Improved access control granularity, allowing access to the bitstream index to be disabled.

Fixed bitstream downloads with storage adapters that don't provide a stream resource for use with fpassthru().

Limited storage adapter selection to available adapters only; added a new API function bitcache_has_adapter().

Improved bitcache_tmpname() to automatically register created temporary files in Drupal's {files} table.

Added a parameter to bitcache_get_path() that can be used to guarantee a local file path will be returned.

- Implemented support for multiple storage adapters that provide backends for Bitcache repositories.
- Factored out the file system storage adapter into adapters/file.inc.
- Implemented a Drupal-specific SQL database storage adapter in adapters/sql.inc.
- Added a storage adapter selection box to the repository creation screen.
- Added a storage adapter listing to the module's settings screen.
- Improved the usability of the repository creation screen.
- Implemented repository-limited bitstream listing and management screens.
- Prevented modification of the default repository or repositories explicitly owned by modules.
- Refactored the storage of repository definitions and related API functions.
- Defined a new database table, {bitcache_data}, to serve as the default Bitcache repository.
- Added schema update #6002 for creating the new {bitcache_data} table.
- Defined a new database table, {bitcache_repositories}, for holding repository definitions and configuration.
- Added schema update #6003 for creating the new {bitcache_repositories} table.
- Added schema update #6004 for migrating repository definitions from the {variable} table to {bitcache_repositories}.
- Provided a new hook, hook_bitcache_algorithms(), for declaring fingerprinting, compression and encryption algorithms.
- Provided a new hook, hook_bitcache_adapters(), for declaring storage adapters for Bitcache.
- Added a new API function bitcache_get_adapters() for retrieving information on available storage adapters.
- Added new API functions bitcache_get_path(), bitcache_get_size(), and bitcache_get_type().
- Added new API functions bitcache_get_schema(), bitcache_get_repository_tables() and bitcache_get_adapter_class().
- Renamed bitcache_get_total_count() to bitcache_get_repository_count().
- Renamed bitcache_get_total_size() to bitcache_get_repository_size().
- Removed bitcache_get_repository_path() and bitcache_get_repository_settings().
- Replaced bitcache_get_repository_proxy() with bitcache_get_repository(NULL).
- Changed Bitcache_Repository from an interface to an abstract base class.

Implemented fingerprint algorithm/encoding and bitstream compression/encryption options for repositories (albeit they are presently disabled until the corresponding backend updates are completed).

Changelog:
- #365077: Prevent timeouts when manually importing a bitstream from a URL.
- Fixed the recommended installation path in README.txt.
- Added a note about the Bitcache command-line tools to INSTALL.txt.
- Implemented a new setting for configuring the path to the Bitcache command-line tools.
- Renamed the previous 'synchronization' setting to 'cron script'.
- Implemented the new API functions bitcache_sync(), bitcache_exec(), bitcache_yaml(), and bitcache_tmpname().