Added SMTP exceptions to return error responses.
Docs for errors module.
Minor typos and edits on docs.
Improved docs about errors module.
Added test case for errors module.
TestCase for __init__ module.
Test case for testing module.
Unused code.
Improved coverage for __init__ module.
Minor edit on docs.
Blank lines raises a UnrecognisedCommand exception.
A exception on request callback must to response as an Internal confusion.
Docs for new manipulation of request callbacks.
Tests for SMTPError with log_message.
Improved index doc, added logo.