Check if Homebrew is install in OS X.
Abstract package installation for OS X, Ubuntu and Arch.
Install OpenOCD from Homebrew instead of from source.
Fix some bootstrap installations on Mac.
Merge branch 'next' into osx-bootstrap

Conflicts:
	script/bootstrap.sh
Don't try and patch FTDI USB Driver in Mac if it's not installed.
Don't fail if FTDIUSB driver isn't loaded yet.