Updates for Vundle/Pathogen

As a result of the discussion in issue #1, I have created this pull request.

It:

  * Moves `autocorrect.vim` to `plugin` and wraps the remaps in a function call

  * Updates the README informing users about how to set up their vimrc to automatically :call AutoCorrect() when files of a certain type are opened, and how to adapt the functionality to their needs in order to get around the speed problem.