Simplify tmux status bar

* Remove administrative debris (session name, hostname, time).
* Soften colors from harsh green to grayscale.
Implement a smarter tab completion function

Credit: Gary Bernhardt
Switch between the last two files
Improve Markdown integration

* Default Vim configuration detects .md files as modula
* Replaces default config so that .md is detected as markdown

Resolves #71.
Add git-churn script

After you commit a bug fix to a feature branch, find out if the code
you changed to fix the bug is in files that change often:

    git-churn

If the buggy code changes often, find smells and refactor them. Separate
the parts that change often from the parts that don't.

Conversely, avoid refactoring areas with low churn. Refactoring changes
code, and with each change, you risk introducing new bugs.

Example:

     [feature-branch][~/dev/rails-app] churn
     2 app/controllers/accepts_controller.rb
     2 config/database.yml
     4 app/helpers/application_helper.rb
     4 config/application.rb
     9 spec/models/user_spec.rb
     9 spec/spec_helper.rb
    12 spec/requests/dashboard_spec.rb
    13 spec/models/feedback_spec.rb
    19 app/models/feedback.rb
    21 app/models/user.rb
Install Vundle

* Set up Vundle in vimrc.
* Delete old copies of vim scripts.
* Bundles are automatically set up as referenced submodules.
* Ignore .netrwhist files given presence of submodules.
* Set up vundle in install script.
Run specs directly from vim

* Run current spec file.
* Run spec nearest cursor.
* Run last spec that was run.
* Convert s alias to s script, use Zeus if present.
Pass all parameters to the executable
Easier editing for Markdown files

* Automatically enable spellchecking
* Automatically wrap at 80 characters
update from upstream