Support setting datasource communities via "Settings" in the meshconfig GUI

[ShawnMcKee]

Add support for super-admins to modify/update the communities used for datasource filtering from the web interface. Currently I see no way to view/add/delete communities that MCA uses to find hosts from the lookup service.

Shawn

[soichih]

Currently, the only way to modify/update the communities is by manually editing the config file and restarting mccache service. At least, the datasource information (which LS instance is queried and with what query) should be displayed via UI.