Allow predefined styles to define different options for different languages.

Summary:
Allow predefined styles to define different options for different
languages so that one can run:
  clang-format -style=google file1.cpp file2.js

or use a single .clang-format file with "BasedOnStyle: Google" for both c++ and
JS files.

Added Google style for JavaScript with "BreakBeforeTernaryOperators" set to
false.

Reviewers: djasper

Reviewed By: djasper

CC: cfe-commits, klimek

Differential Revision: http://llvm-reviews.chandlerc.com/D2364