(Bug 1867) Review code clean up

This patch:

* Standardizes the module name around subscription filter; that's what they're called
  in other areas of the site, so we should be consistent.
* Standardized the SubscriptionFilter class to be consistent in naming; it now has
  a string url var instead of a string link, because the Link class seemed overkill
* Abstracts away the id of the Subscription filter; we can add it in if we need it later
* Improves the logic of adding a filter to the list of filters displayed
(Bug 1867) Add a manage link to the filter module

Implements the same way other management links have been implemented.
(Bug1867) Improve filter module print checks

Now the module checks to see if it should print:

* It shouldn't print for communities or for syncdication journals
* It shouldn't print if there are no filters for it to print