LiquidSmooth Download Center

Based on DU's implmentation added liquid gapps, removed TBu and added rom links

Change-Id: Ibd82a1309ab70d4686f90d7c8c3c357011bf00f8
Downloads to trex
remove changelog
remove xposed
clean up "Download Center"
add Slim gapps (beta) for lollipop in Download Centere