projectile-find-tag: Use ggtags-find-tag if bound
Merge pull request #366 from alanpearce/find-ggtags

projectile-find-tag: Use ggtags-find-tag if bound
* projectile.el (projectile-mode): Fix f71b5f7
Merge pull request #369 from daimrod/fix-compilation-find-file

* projectile.el (projectile-mode): Fix f71b5f7
[Fix #370] A temp workaround

advice-add and advice-remove are only available in Emacs 24.4.