Added "check now" option to menu.
Created new checkNowFromMenu method.

Allows immediate checking from menu bar, even if configuration window
is closed. Thanks @futureimperfect.
"Quit AutoPkgr" to be more specific.
Using constant for app name in Quit menu title.
Merge pull request #54 from lindegroup/check-now-in-menu

Added "check now" option to menu.