[hotfix #28] Check for vars specific to YCM.

  This fixes issue #28.
Merge branch 'hotfix/0.4.6'

* hotfix/0.4.6:
  [hotfix #28] Check for vars specific to YCM.
Merge tag 'v0.4.6' into develop

Hotfix off of v0.4.5

  Includes a bugfix in the event that YCM is not present on the host machine ([#28][1])

[1]: https://github.com/jalcine/cmake.vim/issues/28

* tag 'v0.4.6':
  [hotfix #28] Check for vars specific to YCM.