Implemented formatting of rvalue references

Summary:
Handle "&&" usage as rvalue reference, added tests and fixed incorrect
tests that interfere with this feature.

http://llvm.org/bugs/show_bug.cgi?id=15051

Reviewers: djasper

Reviewed By: djasper

CC: cfe-commits, klimek

Differential Revision: http://llvm-reviews.chandlerc.com/D531

llvm-svn: 176874