Changes on CodingSuite:
1. common.h: Moved class Exception to namespace common to avoid conflict
with Botan::Exception
2. Added KeyException and CodingException
3. Completed thread locking near code using botan random
4. Added hash for secure usage
...
Removed class CodingException for it doesn't seem to be needed.
Added FileConfig so we can read/write text-based configuration from a
file.
TODO: Add a test for it.
Added test and corrections