Android L (re)design

[rock3r]

Create a new widget appearance theming for Android L. This will require a good deal of investigation; some things (e.g. semi-transparent widget BGs) might not be appropriate under L. This will also require updating the Roboto font, the dialogs, and possibly the Switches in the preferences screen. Besides that, it might be appropriate to drop support for pre-ICS Android versions to simplify the code. Only 3% of our users run pre-ICS Android versions anyway.