.gitconfig: Add alias to merge GitHub pull request

Ref. https://help.github.com/articles/checking-out-pull-requests-locally

Closes #422.
Brewfile: add some CTF tools

See https://github.com/ctfs/write-ups for more info.
Brewfile: add binutils and cifer
.osx: Disable transparency in the menu bar and elsewhere on Yosemite
.osx: Remove a few commands that no longer have any effect in Yosemite

Closes #436.
.osx: Use the system-native print preview dialog in Chrome

Closes #434.
.aliases: Update `npm` the right way

`npm install npm -g` is the new recommended way to update npm as specified in the npm-faq at https://github.com/npm/npm/blob/master/doc/misc/npm-faq.md.

Closes #423.
Merge remote-tracking branch 'upstream/master'

* upstream/master:
  .aliases: Update `npm` the right way
  .osx: Use the system-native print preview dialog in Chrome
  .osx: Remove a few commands that no longer have any effect in Yosemite
  .osx: Disable transparency in the menu bar and elsewhere on Yosemite
  Brewfile: add binutils and cifer
  Brewfile: add some CTF tools
  .gitconfig: Add alias to merge GitHub pull request
leave the transparancy settings for now