brew pull: cross-platform bottle verification, concise output (#132)

Do the bottle check using any platform's bottle, so `brew pull` works
on bottled formulae which don't include a bottle for the current system.

Make output more concise and informative
 * Remove expected download error messages when waiting for Bintray publishing
 * Replace patch download progress bars with patch file name
 * Silence git output about switching to and from bottle-pulling branch
 * Include formula name and patch type in some progress messages