New Recording UI

Fix #622

Implemented the layout discussed in the issue as well as some other changes listed below.

- [x] New recording UI layout
- [x] Buttons are now persistent
- [x] All buttons now use only icons
- [x] Custom icons consistent across all platforms (no system icons)
- [x] Record button does not have to remain pressed (Stop button used to look pressed)
- [x] Added "Leave record mode" button
- [x] Output file now gets deleted if never recorded to
- [x] New button style (Record-mode buttons more prominent)
- [x] Moved Auto-Record to Options menu, removed button from Recording UI
- [x] Added Ctrl+R shortcut for auto-record
- [x] Added button to leave auto-record
- [x] Ctrl+R also works in auto-record for leaving

Screenshots:
Windows
![new recording ui](https://cloud.githubusercontent.com/assets/5759678/4585209/f94ef2e6-5002-11e4-9dc3-7ed62119d818.png)
![new recording ui 2](https://cloud.githubusercontent.com/assets/5759678/4585210/fb95dd26-5002-11e4-875d-b59d435550ca.png)

Linux
![new recording ui linux](https://cloud.githubusercontent.com/assets/5759678/4585238/3d08b8aa-5003-11e4-9d85-fc5b56aa9de3.png)
![new recording ui linux 2](https://cloud.githubusercontent.com/assets/5759678/4585239/3d2a7350-5003-11e4-928e-1c83583b81f9.png)


Prefer `os.path.join`