Ensure the correct autoload.php even when composer drupal-update is run instead of composer drupal-update during module init.

- Don't extend ControllerBase because it's not needed.
- Remove unused use statements.
- Fix constructor docs.

- Remove workaround for PHP < 5.5
- Remove unnecessary SafeMarkup usage.

Issue #2452781 followup: Update PackageManager to read the installed packages from the right vendor dir, special case 'composer/installers'.

This reverts commit 9892f9e5.

Raymond Muilwijk authored Apr 30, 2015 and Bojan Živanović committed Apr 30, 2015

Issue #2473969 by joshtaylor, R.Muilwijk, Berdir: composer drupal-rebuild fails with "Required prefix configuration is missing"

Revert "Issue #2473969 by joshtaylor, R.Muilwijk, Berdir: composer drupal-rebuild fails with "Required prefix configuration is missing""

This reverts commit a878b02a.

Sascha Grossenbacher authored Apr 22, 2015 and Bojan Živanović committed Apr 22, 2015

Issue #2473969 by joshtaylor, R.Muilwijk, Berdir: composer drupal-rebuild fails with "Required prefix configuration is missing"

Fix 'composer drupal-update' bug when the command is invoked with an option before the command name.

Clean up the property gathering and resolving in RootPackageBuilder to make it easier to collect additional properties in the future.

Allow for the SKIP_COMPOSER_UPDATE environment variable to skip 'composer drupal-update' after drush dl.

Fix PackageManager to take the package constraint from the dependent package requirement, if available.

Make sure PackageManager::processRequiredPackages() adds default values first, to prevent notices when determining dependent packages.