The chromium style guide allows the use of c++14 features
(https://chromium-cpp.appspot.com/).
Thus ycm should use c++14 by default.

R=bmeurer@chromium.org

Change-Id: I6eca99931d117ad57213e8c6e18e75d83b7fd675
Reviewed-on: https://chromium-review.googlesource.com/789873Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49624}