Implement ticker widgets

This is adding in a small app I wrote some time ago to enable ticker widgets on Android.

Initially, implement 'as-is'; which displays the tickers for various cryptos such as Bitcoin, Litecoin etc.

Once this is working, add in Tokens from Ethereum and other chains.

In completing this you'll have to use:

- Foreground service
- Background service
- Service update of widgets on home page

Initially:

- [ ] allow user to place widgets on home screen, being able to set to one of the listed chains.
- [ ] update chain tickers on periodic update.

Then:

- [ ] allow user to select from tokens that have a ticker (the activity pops up when you add the widget or click on it on the home screen)