.functions: Improve `targz`

* Only use `zopfli` when it’s available and if the `.tar` file is smaller than 50 MB.
* Use `pigz` instead of `gzip` when it’s available.
* Always exclude `.DS_Store` files when creating a tarball.

Closes #199.
bootstrap.sh: Don’t make the home directory world-readable

Fixes #159.
.brew: Install native apps through homebrew-cask

Closes #200.
.brew: Add some more applications
.osx: Update filename for Dropbox’s green checkmark icon
README: Update contributors list

Add @sindresorhus and @alrra because of their many contributions. Sort the list alphabetically.
README: Fix minor typo
.functions: Tweak `targz`

Trim the trailing slash from the path argument passed to `targz`.

This fixes the annoying behavior where `targz foo/` created `foo/.tar.gz` instead of `foo.tar.gz`.

Ref. #202.
.gitconfig: Use `push.default = matching`

I couldn’t get used to `simple`.
.functions: Add `gi`

This is an easy way to install Grunt plugins and add them as `devDependencies` to `package.json`.
Example:

    gi contrib-watch contrib-uglify zopfli

Closes #191.
.functions: Improve `note`

Give the Notes.app function the ability to add both `title` and `body`.

Closes #203.
.functions: Improve `httpcompression` and move it to its own file

Closes #162.
Dual license these dotfiles under MIT/GPL

As requested by @lathan. Closes #205.
.osx: Fix `ShowPathBar` typo

Closes #204.
.bash_profile: Try to grunt more quietly

Ref. #209.
.functions: Add `gitio`

Closes #210.
.osx: Don’t automatically rearrange Spaces

Closes #213.
.gitconfig: Tweak `l` alias
Update to Bash v4.2.45
.osx: Update the GitHub fork link

Closes #221.