[aur-general] Delete vim-notmuch

Hi, I packaged this plug-in as a standalon vim plug-in, however, nowadays it's bundled with the official 'notmuch-vim' package already. In theory I could update the package for the people that want to have the latest and greatest version without having to wait for a notmuch release. However, those people are better served by using a plug-in manager like pathogen and use the Git repository. Cheers. -- Felipe Contreras