Add code from service.pushbullet.com (ruuk)

I changed the version to 0.7.0b I figured this is a pretty big change :)

You'll notice that other than my added code, I modified very little of your code.

Some notes on my changes:

Running Pushbullet from Programs will now start the interface or prompt the user to authorize if the token is not set.

I removed the code for automatically creating a device, and replaced it with my code that allows either creating a new device and choosing a name, or selecting an existing device. This gives the user more control and allows them to add multiple Kodi devices. The old method would create multiple same name devices on Pushbullet if it was run from multiple devices.
The service code will now not run unless both the token and device iden are set.

Links are now run through my code. I've only got it handling video so far. I'm going to add some settings for the user to enable what push types they want automatically displayed before adding handling for them.

There is still a bit that needs cleaned up - extra strings in strings.po, the settings could be re-organized, some of the code could be simplified, for instance I could probably remove some of the functions from my util.py and use the ones in common.py and move the remaining functions there.

Videos played from pushes will not currently trigger a call to sendEphemeral() because they don't have a title like the youtube plugin supplied. I think I can fix this by using xbmc.Player().play() and passing in a ListItem with the title and other info.

I don't think I broke any of your code, but I haven't tested any of the stuff that didn't affect the code I added.

Below are links to module dependencies that you need installed. The script.module.oauth.helper module isn't in the official repository yet so I'll need to add it before we release the combined version.

http://mirrors.xbmc.org/addons/frodo/script.module.requests/script.module.requests-2.3.0.zip
http://mirrors.xbmc.org/addons/gotham/script.module.youtube.dl/script.module.youtube.dl-14.925.0.zip
https://ruuks-repo.googlecode.com/svn/trunk/repo/script.module.oauth.helper/script.module.oauth.helper-0.0.7.zip
what do you think, something like:
```import os
from lib.common import __addonpath__```