Add ASTMatchRefactorer and ReplaceNodeWithTemplate to RefactoringCallbacks

Summary: This is the first change as part of developing a clang-query based search and replace tool.

Reviewers: klimek, bkramer, ioeric, sbenza, jbangert

Reviewed By: ioeric, jbangert

Subscribers: sbenza, ioeric, cfe-commits

Patch by Julian Bangert!

Differential Revision: https://reviews.llvm.org/D29621

llvm-svn: 302624