Add a portal transform using the stand-alone converter.
Add an uninstall profile.
Allow for Tika JAR path to be configured via ZCML directive.
Include a tika.cfg buildout to download Tika.
Include instructions on how to use transform caching in README.

Closes #4
Make sure transform catches and logs exceptions instead of raising them.

Closes #3
Use filename for logging during conversion (if supplied).

Closes #2
Slightly refactor test setup.
Properly deal with existing transform policies:

- Unregister earlier version of our own policy from previous installs
- Raise exception if any other policy for text/plain is present.

Closes #6
Update supported MIME types to include most common office document formats.