Settings: give a custom build number

Hardcoding the build number only in Settings app,
instead of changing the detailed build number through
build Makefile. This preserves the actual detailed info
in build ID string as well as shows "Android Open
Grand Project" in the settings app.

Squashed commit of the following:

commit 99187818a233c3b6c790957f227dcffd424d58f2
Author: Shubhang Rathore <shubhang92@gmail.com>
Date:   Thu Aug 7 09:50:47 2014 -0400

    Revert "Settings: remove build number preference"

    This reverts commit e8684304656ffb38a13d34e83506804dac989adf.

commit 38facece762308d334cd765c31e6ecc8af6942ba
Author: Shubhang Rathore <shubhang92@gmail.com>
Date:   Thu Aug 7 09:50:17 2014 -0400

    Settings: give a custom build number

    Change-Id: If1667b412ec662d1600892f2cca8aaabb1828d3d

Change-Id: I0cabcf17ea6225c74d21e9d9c359690aeb29508e