Initial commit for ScanFilter.

This closes #51.

Signed-off-by: Benoit Sigoure <tsunanet@gmail.com>
Add Viral to AUTHORS for his work on ScanFilter.

Add also my current employer.
Document ScanFilter and prevent it from being subclassed externally.
Convert the regexp key filtering mechanism to the ScanFilter.

Add an integration test to ensure this didn't break in the process.
Document how to run integration tests.
Add more scanner filters.

Signed-off-by: Benoit Sigoure <tsunanet@gmail.com>
Enhance filters a bit and add integration tests.

Summary:
  - Make filter classes final.
  - Add Javadoc.
  - Add helper functions to be able to pass String objects in argument.
  - Add toString() methods.
Add a new helper function to produce better errors during tests.