Added DSA digital signature algorithm classes and functionality and tests
changed exception catching according to Coryt
's comments
changed exception catching according to Cory's comments
exception handling
Merge pull request #26 from jmaheswaran/master

Added DSA digital signature algorithm classes and functionality and tests
Merge pull request #27 from darylseah/master

Add native file-system key storage driver (and other minor changes)
changed exception handling
Merge pull request #28 from jmaheswaran/master

changed exception handling to be pre Java 1.7 compatible
Remove unnecessary throws.
Make info annotations inheritable.

- More convenient for implementations.
- Modified unit test to work with this.