add ubuntu platform
CB-5188:
1. Added amazon-fireos platform.
2. Change to use amazon-fireos as a platform if user agent string contains 'cordova-amazon-fireos'.
added beep funtionality using ms-winsoundevent:Notfication.Default
Merge branch 'dev' of github.com:archananaik/cordova-plugin-dialogs into dev
added ubuntu support
[CB-5565] Updated version and RELEASENOTES.md for release 0.2.4
Merge branch 'dev'