Extend GitChangeLogCommand by using revision only

Invoking execution of a GitChangeLogCommand where only the end revision has been set produces a wrong out.

Actual result:

git whatchanged --date=iso  ..END_REVISION_SHA1 -- PROJECT_PATH

Expected result: only the end revison SHA1 is used without the two dots

git whatchanged --date=iso  END_REVISION_SHA1 -- PROJECT_PATH