In host's edit page, show the source for the value of puppet class parameters

Currently, on the edit hosts page, under the parameters tab, if a parameter was overridden in the host's hostgroup (or that hostgroup's hostgroup), the additional information popup for that parameter says "Matcher: hostgroup."

![screen shot 2014-08-07 at 5 33 25 pm](https://cloud.githubusercontent.com/assets/4042349/3851389/fc038b6e-1e93-11e4-9e80-41d775df765c.png)

This is not very useful because the parameter's value could be coming from the hostgroup or a grandparent hostgroup. It would be more useful to display the actual hostgroup's name so that we know precisely from which parent the parameter's overridden value is coming from. 

![screen shot 2014-08-07 at 5 39 05 pm](https://cloud.githubusercontent.com/assets/4042349/3851415/7660d574-1e94-11e4-822d-df05ebc84b39.png)

Tests are failing on PostgreSQL and SQLite, seems that pc.id has a different ID, but I'm not sure why.  @orrabin would you mind taking a closer look?  thanks