Feature/remove janus

* Remove janus from dotfiles (i.e. move directories and files around to resemble normal vim structure)
* Add vim plugins that I use (only the ones I use, to improve startup time)
* Update installation script to symlink folders correctly
* Extend .vimrc with settings from [Eoin Kelly](https://github.com/eoinkelly) and _some_ settings from [Janus](https://github.com/carlhuda/janus)
* Configure pathogen to load vim plugins from, well, plugins.