[Fix #1289] Use utf-8 as default encoding for inspected files

For all Ruby versions.
Merge pull request #1322 from jonas054/1289_default_encoding

[Fix #1289] Use utf-8 as default encoding for inspected files
[Fix #1304] Style/Encoding is no longer a no-op on Ruby 2.x

It's also disabled by default, as projects not supporting 1.9 don't need
to run it.
Make it possible to ignore certain methods in SymbolProc
Cut 0.26.0
add autocorrect for UselessAccessModifier

update CHANGELOG

rubocop cleanup

update pull request number in CHANGELOG

fix failing cli_spec

rubocop cleanup