Remove unused submodules directories.

Running `rake install`, runs the `:submodule_init` task,
which in turn runs the following command:

    git submodule update --init --recursive

This fails with the following couple of errors (separately):

    No submodule mapping found in .gitmodules for path 'vim/bundle/mattn-zencoding-vim'
    No submodule mapping found in .gitmodules for path 'vim/bundle/skwp-vim-indexed-search'

This was introduced by 3d60f721dd53e7f5414d11004c749784efc74f64
which removed the 'mattn/zencoding-vim' and 'skwp/vim-indexed-search'
submodules from the `.gitmodules`.
Merge pull request #243 from gonzedge/submodules-init

Remove unused submodules directories.
Vim plugins and prezto updated
Improved sass colors
Remove arpeggio; unused
Added vim-gitgutter, which shows git diff in the gutter
Upgrade plugins
Merge pull request #246 from irrationalfab/vim-gitgutter

Added vim-gitgutter, which shows git diff in the gutter
Upgrade plugins
Remove gitgutter; causes errors
Add gitgutter
Merge pull request #247 from irrationalfab/vim-gitgutter

Add gitgutter
Removed unused / not working ,,f ,,F aliases
Readme cleanup
Renamed vim/plugion/settings/fugitive.git to vim/plugin/settings/fugitive.vim. Fixes issue #249
Removed unused plugin ruby_focused_unit_test
Merge pull request #250 from kmees/issue_249

Renamed vim/plugion/settings/fugitive.git to vim/plugin/settings/fugitiv...
Updated subprojects
Added ,mm to switch to mailer while in view
Revert "Added ,mm to switch to mailer while in view"

Conflicted with showmarks in an ugly way
This reverts commit 44a2cd79d09aea86c464d4880d5fdfe8b378d7ce.