bliss: Add Internal Bliss OTA Updater (BlissOTA) [3/4]

If your device is Officially Supported by BlissRoms,
then maintainers whenever you build a new build a ota.xml file will be generated automatically.
Device maintainers have to upload ota.xml with every build to reflact the new changes.
backuptool.sh updated to use different build.prop entry
for version check.

Added to build an automatic ota.xml generation script.
In .bashrc add the following line (and reopen terminal):
export BLISS_DEVELOPER=yourXDAname
export BLISS_DONATE=yourDonateURL
Important: use goo.gl for donate URL!

Thanks to Kryten2k35 for the source, nicholaschum, tobitege, jackeagle and
genesixxbf3 for the implementation!

Change-Id: Ibc84c9620a38603b5944203193b220fbe669ad28
Signed-off-by: Jackeagle <jackeagle102@gmail.com>
7 files changed