Big UI Commit

HomeViewActivity changes:
- Four test topics created
- ListView elements cleaned up, using table layouts
- Added Saved Pages button
- Added New Topic button
- Changed background color to default theme
- Added dividers between topic listings, removed alternating colours
- Set activity as "home" in manifest for "up" button functionality

CreateTopicActivity changes:
- Layout cleaned up using tables
- Added icons
- Added image buttons, aligned in a RealtiveLayout
- Added topic label
- Added "up" button to return to HomeViewActivity
- Added entries to @strings for activity name and "Submit" button

TODO:

For HomeViewActivity:
- Add Sort spinner to Action Bar
- Link Saved Pages button

For CreateTopicActivity:
- Link attach photo/location buttons