- lexer.rl: "{'x':1,'y':{}}": fix lex_state after tLABEL_END.

This commit tracks upstream commit ruby/ruby@cbdac1ea.
Bump version.
Update changelog.
- Update syntax deviation warning to reflect 2.2 release.
ruby22.y: remove incomplete parser warning.
- lexer.rl, lexer/literal: "{'a'::": don't parse as quoted label.

Fixes #177.
Bump version.
.travis.yml: add 2.2, disallow failure on head.
Update changelog.
Merge remote-tracking branch 'whitequark/master'