LibClang for llvm-3.4 & rtags-rename-symbol

Two trivial changes:

1. add an additional libclang path for llvm debian/Ubuntu nightly,
http://llvm.org/apt/
in this case index.h is in /usr/lib/llvm-3.4/include/clang-c/ rather
than the canonical one

2. an additional save buffer operation is added after
rtags-rename-symbol
Merge branch 'master' into chx
Merge pull request #115 from HongxuChen/chx

LibClang for llvm-3.4 & rtags-rename-symbol