Code review comment for lp:~adeuring/charms/precise/juju-reports/juju-reports-new-revno-in-new-dir

The charm now uses a shared repository. I've also added some logic to check if the revno has changed between two calls of the config-changed hook: The current revno and parent branch URL are stored a file "last-source-revision"; update_source() and install_production() are now called only when the current config has other branch URL/revo values than before.

The config parameter "dist-clean" is has not real usage in the strict sense since juju-reports is now always built in a new directory; I've added logic so that update_source() and install_production() are always called when dist-clean is true. Similary, the revno value -1 cause a new build in each config-chaned run. (This should be improved: We can check if the parent branch has a new revision.)

Finally I noticed that the install hook still removed the directory $home/juju-reports. This is done in make_project_link(), so I removed it.