Pretty-print the CL description during commit.

Having "Description: u'Foo\nBUG=1234\nR=bar@chromium.org\nReview Url: baz'"
is not actually that useful in my experience. I'd rather be able to easily
read the final CL description that is being committed.

Review URL: https://chromiumcodereview.appspot.com/23185006

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@217834 0039d316-1c4b-4281-b951-d872f2087c98