introduction of a new "About application" page

+ version number from Manifest
+ urls for license, list of changes, support, bugreports
+ copyright text on the about page
+ based on concepts as found in https://github.com/schildbach/bitcoin-wallet
+ theme-aware page (dark/light design)
+ returns correctly from web pages (like source code, support forum) to the About page

The copyright message in the new sources files is now:

+ (C) 2014 Open Whisper Systems and the original author or authors.