Gerrit Dialog - renamed "Apply" to "Cherry Pick"

Cherry pick is git command that everyone who works with git knows. First
time I saw "Apply" I thought it was some git or gerrit command unknown
to me. Renaming it to "Cherry Pick" makes dialog more clear, since user
knows what command will execute when button is pressed.

Change-Id: Ifbcad697ef5f5909a36dc008f716025d48a26ad0
Reviewed-by: Orgad Shaneh <orgads@gmail.com>