Correct filter when displaying GA gadget in the context of a page

Description

When displaying the Google Analytics (GA) gadget in the context of page, GA data is filtered by the page path and host name. Currently, only one host name (site host name) is included in the filter. This is incorrect because the page can be accessed from multiple hosts.
To define hosts for the site, go to Admin > Config > Manage Websites. Only hosts belonging to the site are used to filter data for GA.

Additionally, in some cases the GA's view can be applied a filter that includes host name in the URI (this is common), so there is no data displayed when select the view (see GA-36).
GA add-on should support this case and be extensible for other cases.