[PATCH] Config file support for clang-format, part 2.

[Alexander Kornienko]

  I've tried, of course. And my message goes after YAML I/O's, but this way
  it's still informative enough for diagnostic purposes. And I thought we can
  come back to this once YAML I/O has better support for this.

http://llvm-reviews.chandlerc.com/D758