Add a capability to indicate support for Perforce moved files.
Review Request #3790 — Created Jan. 26, 2013 and submitted
Add a capability to indicate support for Perforce moved files. 1.7.2 introduced moved file support for Perforce, but there wasn't a good way for RBTools to really detect this that retained compatibility with previous versions of Review Board. The reason is that we relied upon the existing general diffs.moved_files capability, causing RBTools to generate diffs for older releases that ended up being incompatible. This introduces a scmtools.perforce.moved_files cap that can be used instead. 1.7.3 will be the minimum version of Review Board that will support moved files for Perforce with RBTools.
Checked that the capability was in the payload. Made sure no existing tests broke.