Support the move of Qt 5.1 docs from "dev" to "stable"

Make sure the transition from "dev" to "stable" is as smooth and seemless as possible.

-the doc-snapshot.qt-project.org should build the latest snapshots
-make sure that new modules are linked from the main site.
-other git/codereview issues that come up with regards to Qt 5.1

When the build system is stable, then we can close this task.