New dream settings - first cut

First draft implementation of mocks for dream settings.

Want to merge for the weekly build, so a few things remain, namely:
  - flat style for preview/settings buttons + dividers
  - animation between dream row expanded/collapsed state
  - wire up the help url
  - possibly ditch the non-standard style
  - add logging
  - refresh when packages are installed/uninstalled

Bug:7010260
Change-Id: I96e3ab944170925bd76edf7b8b1127adfffc6262