[clang-refactor] Add "-Inplace" option to the commandline tool.

Summary:
Change clang-refactor default behavior to print the new code after refactoring
(instead of editing the source files), which would make it easier to use
and debug the refactoring action.

Reviewers: arphaman, ioeric

Reviewed By: arphaman

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D39092

llvm-svn: 316212