Ensure visibility flags persist across a commit.
Documentation cleanup.
Prevent uncaught JS errors for unplaced units.
Merge pull request #655 from kadams54/fade-placed-unit

Ensure visibility flags persist across commit

When a ghost unit is committed, the actual unit is deleted and then the new, real unit is added based on data from juju-core. We need to copy the visibility flags down from the service during that process.