.gitconfig: Tweak `l` alias
Update to Bash v4.2.45
.osx: Update the GitHub fork link

Closes #221.
Remove GPL license

The MIT license is GPL-compatible anyway, as per @sindresorhus. Ref. https://github.com/mathiasbynens/dotfiles/commit/a89e2f2d226de274c998b0b8de5fd4af2e0b444f#commitcomment-3485954.
bootstrap.sh: Avoid `source` if there are no changes

Closes #220.
.aliases: Make Grunt print stack traces by default
Merge branch 'master' of https://github.com/mathiasbynens/dotfiles

# By Mathias Bynens (4) and others
# Via Mathias Bynens
* 'master' of https://github.com/mathiasbynens/dotfiles:
  .aliases: Make Grunt print stack traces by default
  bootstrap.sh: Avoid `source` if there are no changes
  Remove GPL license
  .osx: Update the GitHub fork link
  Update to Bash v4.2.45
  .gitconfig: Tweak `l` alias