Small cleanup of vimrc and gvimrc

- Spelling
- Formatting
- Removed a few extraneous settings
- Clarified comments
- Normalized quotation marks
Use MacVim's bundled executable when available
Amend PATH for Homebrew-managed PHP 5.4
Add git hooks for ctags

See: http://tbaggery.com/2011/08/08/effortless-ctags-with-git.html