Log Message:
Update ruby-parser to 3.7.0.

=== 3.7.0 / 2015-05-28

* 2 major enhancements:

  * Added preliminary support for ruby 2.2 syntax.
  * Now writing all 2.x parsers from one source, generating racc files.

* 1 minor enhancement:

  * Added RubyLexer#process_label and hooked it up to "x": and 'x': \ 
productions.

* 4 bug fixes:

  * Fixed handling of block_args to be consistent across all parse versions.
  * Fixed lexing of label assoc args w/ newlines in between k/v. (jeremyf)
  * Fixed lexing of x?'':y for ruby22 (not a label). (presidentbeef)
  * clear and restore cmdarg stack around def args and body.

=== 3.6.6 / 2015-04-13

* 1 minor enhancement:

  * Added expr_labelarg state (eg: a:1)

* 5 bug fixes:

  * Fix scan logging backtrace when DEBUG=1
  * Fixed kwsplat on 2.0 & 2.1.
  * Fixed mandatory keyword block args. (cvortmann)
  * Handle #$<x> in expanded strings/regexps where x is NOT a valid gvar name.
  * Invalid gvar names raise a compile error.