Shorten regex blacklisting bad filenames.
Merge pull request #29 from darylseah/master

Add unit tests for RegisteredKeyVersion and KeyVersionRegistry.
Merge branch 'master' of https://github.com/google/K2
Refactoring of storage driver interfaces.

- Renamed StoreDriver/StoreDriverInfo to Driver/DriverInfo.
- Moved all to com.google.k2crypto.storage.driver.
- Split Driver interface into Readable, Writable and
  Wrapping(Driver), for better extensibility.
- Removed attributes from DriverInfo to avoid extensibility
  issues.
- Add documentation for package.
Add "write-only" to UnsupportedByStoreException.Reason.
Add "useless" to StorageDriverException.Reason.
Move AddressUtilities and unit test.

- The utilities are now considered part of the "driver" package.
Refactor mock storage driver.

- Conforming to latest driver specifications.
- Remove "Store" from names.
Update InstalledDriver to query new driver interfaces.
Update storage impl to use new Driver interface.
Add javadoc for storage package.
Update K2FileSystemDriver to use new driver API.

- Move to com.google.k2crypto.storage.driver.impl package.
- Driver now only implements Read/Write interface
  (excludes Wrapping interface for now).
- Update unit tests to match.
- Add javadoc for package.