[Service][VD] Apply DeviceHome as squashfs format

[Service][VD] Apply DeviceHome as squashfs format

This patch is uploaded again, and chmod 755 to
/usr/apps/.preload-rw-wgt/device_home.tmg to avoid
create image fail in Cosmos.

Apply squashfs app to reduce app size in TV profile.
This will reduce DeviceHome application 9.2MB(unzipped) --> 1.9MB

Plus, this removes DeviceHome's onboot option either. DeviceHome will
be launched by wrt-service-broker.

Note.
privileged-service should add mount policies for wgt-backend first.
Then, this patch can release to VD p4

Change-Id: Ief92f8a780b3b7cd28596f86c5239c96f25e3aba
Signed-off-by: liwei <wei90727.li@samsung.com>