DC: fixup bootup service and other cleanups

*) remove unneeded throws in RootTools
*) change the way how cpu states are displayed
*) use our custom preferences for the build.prop modder quick tweaks
*) fix gpu frequency and governor not restoring
*) clean up the bootupservice, build command strings in their class and
   return the command, which will get executed after all
   commands are collected.
*) memory tweaks, do not create zero length arrays, move pmList
*) other small fixes

Change-Id: I69afbc8c8bf57cdbe177dbb63c5fec69b5d5c362