Adds refresh

Adds refresh button.
Make file automatically if it does not exist

Remove readline import (this is Tk, we don't need console)
Remove coding line (we don't use any UTF-8 characters)
Add appdirs (find application data folder on various OSes)
- Add appdirs import
Handle files as list
Replace "if not in, do stuff" with "if in, skip" for cleanliness
Change name from "add" to "f" (clearer)
Fix #9 - Merge refresh

Merge refresh and also refactor it
- Move pile of shared code into `mainGUI(text)`
- Make entries and websites use `.append()`
- Refresh when subscribing to new feeds
Fix to comply with pep8 guidelines
Improve file creation - Fix #10
Re-add UTF-8 coding
Move main code to bottom
Fix #11 - Add data dirs
Merge pull request #12 from powderblock/userdata-dir

Use user data directory for storage