add ubuntu platform
CB-5188:
1. Updated platform name amazon->amazon-fireos. Deleted src files.
2. Change to use amazon-fireos as the platform if user agent string contains 'cordova-amazon-fireos'
wp8 add support in level
added ubuntu support
Merge branch 'CB-5243' of https://github.com/pu-chen/cordova-plugin-battery-status into dev
Merged WP8 support for level, but #def'd it out so the same code runs on wp7.  Updated docs to reflect WP8 support for battery level, and low+critical events
[CB-5565] Updated version and RELEASENOTES.md for release 0.2.5