WrtDAO clean up - unused function with widget handle usage

WrtDAO clean up - unused function with widget handle usage

[Issue#]       N/A
[Bug]          Unused functions of wrtDAO
[Cause]        N/A
[Solution]     This removes unused methods and add registerWidget method version which generates free tizen id (this is for purpose of rewriting wrt-tests-dao without widget handle)
[Verification] build all repositories, wrt-installer should be still able to install, uninstall widgets. Run: wrt-tests-dao --output=text --regexp='widget_dao_'. Two tests fails. This will be fixed in wrt-extra commit.

Change-Id: Ib0155b240c1776d104fc0e48e5ffaa854468eb97