Issue #2376775 by eshta: Fix Acquia Lift Web Admin link href to be dynam...

...ically read from API url configuration setting.
I'm adding in the part to strip it out of the config form and a test for that.  I don't think I need to change the protocol here, however, as this is checking to see if it is the default value saved in the install (which has an external link path of 'http://lift.acquia.com').  And we aren't making a call or including anything... we are simply adding a menu link to the admin.