Dump uchroot, add hybris and platform-api repos

Signed-off-by: Jani Monoses <jani@ubuntu.com>
Merge remote-tracking branch 'phablet/phablet-saucy' into default
Go back to using only vision hardware-specific repos on top of Canonicals' upstream repos, no more custom replacements for display, media, … repos.

Change-Id: Ic0cf1841d236ea1a73586d900ddc7f0a7351e9f2