Git push to current, not upstream

The primary use case for me is to `git push staging` and `git push
production` from the master branch using our typical git workflow:

https://github.com/thoughtbot/guides/tree/master/protocol#deploy
Make the migrate alias faster

This was loading up the environment four times when it really only needs
to happen twice.
Remove unused vim plugins

* haml, html and markdown highlight still work without these plugins
* treetop and textile are likely very situational
* unsure if anyone is using greplace
Remove old ignores

* sass gets compiled to `tmp/sass-cache` with Rails
* vendor/bundle_gems seems like an arbitrary vendor directory
* vim/.netrwhist is for a plugin we no longer use
List local files available to override
fix relative .aliases.local path
Add syntax highlighting to certain file types

* Syntax highlight `Appraisals` as Ruby. Used especially for our open
  source libraries.
* Syntax highlight rackup (`config.ru`) files as Ruby. Used in all our
  Ruby web apps. Rails apps are rarely touched but some of the Sinatra
  and Middleman apps are occasionally edited.
* Syntax highlight JSON files as JavaScript. Used in our Trail Map.
Remove redundant syntax highlighting

Newer versions of vim (such as 7.3.923) syntax highlight Rackup and JSON
files correctly. In the interest of keeping the dotfiles slim and our
machines up-to-date, I think the solution is to remove these from
dotfiles and install a newer version of vim in thoughtbot/laptop:

https://github.com/thoughtbot/laptop/pull/118
Adds local configuration file for vim bundles
Allow for a local tmux.config file