Allow posting submitted changes in perforce

Review Request #7467 — Created June 29, 2015 and submitted — Latest diff uploaded

Information

RBTools
release-0.7.x
7562be5...

Reviewers

Recent changes to the Perforce SCMClient regressed the ability of
posting submitted changes. This patch addresses that issue.

Ran unit tests.

Attempted to post a submitted changelist with rbt. It failed
without the patch applied and succeeded with it applied.