matchbox-session-sato: install GConf values directly instead of using schemas

matchbox-session-sato: install GConf values directly instead of using schemas

Because both matchbox-session-sato and settings-daemon were attempting to
install their preferred values though schemas there was a race as to which ones
were used.

Revert matchbox-session-sato back to writing the values directly, adding a
dependency on gconf-native so that this can happen on the host.

(From OE-Core rev: 90ca53cbbdb1ed30883d4aa8ce9c933ae1fad5fa)

Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>