New activity tabs - filter box cleanup

[Ezd]

Right now there's a filter box on each of the 4 new tabs under Activity in your profile:
Friends, Groups, Favorites and @ Mentions.

• The filter box under "Favorites" isn't working (should it even be here as your only able to mark updates as Favorites now?)
• Under the Groups tab you can right now filter on a lot of different things then just groups.
• @ Mentions is probably ok if it's possible to mention users in the forum, in blogs ect? If not maybe it's a bit overkill to include everything filter option here.

[apeatling]

I've limited options when looking at group activity. I think @mention filters are fine.

[apeatling]

(In [2491]) Fixes #1738