[Fix #490] Add EnforcedStyle config option to TrailingBlankLines
Remove FinalNewline cop

It is no longer needed. The same check is done by TrailingBlankLines.
Remove special logic for avoiding TrailingWhitespace clobbering

This is done on a higher level now, so no need to do it in the cops.
Merge pull request #991 from jonas054/configurable_trailing_blank_lines

Configurable trailing blank lines