Add 'AlreadyInitalized' to arcpy.CheckExtension function.

Idea created by lpinner on Feb 10, 2015
    New
    Score30
    • mlou
    • lpinner
    • vmansbridge1
    So we can check if an extension has already been checked out manually and not check it back in at the end of the script. See https://geonet.esri.com/thread/121431 and http://gis.stackexchange.com/q/133906/2856 for more info.