Adaptation to the released GitHub API 1.45

The Kohsuke's GitHub API 1.44-SNAPSHOT did not include
all of my proposed changes: need then to adapt to 
what has been included in Ver. 1.45 even by making
one extra GitHub API call (that I wanted to avoid)
to fetch the project again. 

Change-Id: I803ac1dbb615366f662c2515bf0ac84d56acd820