Fix download location; implement consistent naming

- Fixed download location (../tmp/foo.txt) -> (../Library/Text Files/foo.txt)
- Attempt to fix compiler complaining about frameworks; failed
- Updated known issues
Removed references to old file storage headers
Extract gradient background

- Extracted gradient background code to a new
UIView. Import separately to each class.
Add custom segue

- Add custom segue. Subclassed UIStoryboardSegue.
Implement two properties to be set on transition
- Neglected to change branches...