Add transparent dash support to commands.
Add transparent dash support to commands.

This makes it easier to type without using the shift-key, so an user can type
'git cl set-commit' and it'll find CMDset_commit.

R=xusydoc@chromium.org
BUG=

Review URL: https://chromiumcodereview.appspot.com/22918019

git-svn-id: bd64dd6fa6f3f0ed0c0666d1018379882b742947@219054 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

svn2github/chromium-depot-tools,svn2github/chromium-depot-tools,svn2github/chromium-depot-tools