Updated RSSActivity to a ViewPager, added Get Involved to RSSFeed

- RSSActivity now displays all feeds in RSSFeed, instead of the user choosing which feed to display, all the feeds are displayed in a ViewPager that a user can flip through.

- Get Involved is now implemented into both the in-app rss feeds and the widget. I've set is up so that all someone needs to do to add new feeds is to simply add them to the RSSFeed enum. This is assuming that the feeds they add has similar formatting to the feeds already present.

- Added hardware acceleration to fix scrolling lag. I don't know if this was on everyone's device but when I tested it on my phone scrolling would cause lag when trying to render a large amount of text.