- Changed encryption method checker to catch invalid methods.

- Changing occurrances of drupal_strlen and drupal_substr to strlen and substr, respectively. Not sure what is happening, but the drupal_ wrappers appear to be dealing with encoding incorrectly.
- Finishing up tests.

- Tests for each of the implemented encryption methods. ("Basic" doesn't work currently?)

* This modules provides a simple API for two-way
  encryption.