Credited contributors and fixed lack of periods at the end of changelog lines.
Merge pull request #568 from dblock/changelog

Credited contributors and fixed lack of periods at the end of changelog lines.
Fix StringLiterals bug regarding character literals.

The StringLiterals cop shold not report offences for character literals.
Make more precise corrections in autocorrect.

Calling corrector.replace with rather big ranges increases the risk for clobbering, i.e. conflicting corrections. It's better to use insert_before, insert_after, and remove when possible, and replace only when it's relevant.
Fix double reporting of offence in SignalException.