Add CMassiveGitTaskBase as the base class of CMassiveGitTask

This is to isolate UI class

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>
Introduce CGit::DeleteRemoteRefs()

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>
Call CGit::DeleteRemoteRefs() to delete remote tags

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>
Call CGit::DeleteRemoteRefs() to delete remote branch

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>