Remove duplicate entry for plugin
Configuration for unite.vim, remove unused sources

Added the following unite.vim mappings:

* <C-p> opens in the current buffer a list of all local files
* <C-b> opens in the current buffer a list of all current buffers
* <C-f> opens in the current buffer a list of all lines in the current
  buffer

Configured the following unite.vim settings:

* file_rec/async and buffer set to ingore .git/ and tmp/ directories
* start_insert set to not start unite in insert mode
* default matcher set to perform fuzzy matching
* default sorter set to use rank sorter