Update Command-Line-Reference.markdown

The Push command description, "Pushes...and optionally publishes" implies you can push without publishing.  I believe this is not possible (otherwise this description should say how to push without publishing).  I have deleted "optionally" so it says "Pushes...and publishes".
Merge pull request #120 from BruceHaley/patch-2

Update Command-Line-Reference.markdown