.gitconfig: Add `dm` alias

`git dm` deletes local branches that have been merged with master.

Closes #309.
init: Tweak Sublime Text settings
.osx: Add Activity Monitor settings
.osx: Add Finder ‘Get Info’ settings
Merge commit 'bcef5e2d969b706139803f607b421903431917c7'

* commit 'bcef5e2d969b706139803f607b421903431917c7':
  .osx: Add Finder ‘Get Info’ settings
  .osx: Add Activity Monitor settings
  init: Tweak Sublime Text settings
  .gitconfig: Add `dm` alias