[FIXED JENKINS-17417] Expand Branch Specifier

Expand Branch Specifier with build environment variables.

Note that the Branch Specifier is not expanded for repository polling
because no build environment is available at that time.
close changelog.xml after reading
[FIXED JENKINS-20585]
Merge pull request #183 from hrubi/expand-branch-spec

[FIXED JENKINS-17417] Expand Branch Specifier
Merge pull request #198 from wannessels/fix-locked

close changelog.xml after reading
Merge pull request #197 from wannessels/master

[FIXED JENKINS-20445] [FIXED JENKINS-20387] [FIXED JENKINS-20750]
fixed compile error on backward compatibility
added default timeout to GitSCMBackwardCompatibility.useShallowClone