Add more info while flashing

Change-Id: I6ada4cb5b2962073037b28045ca8304d602155c4
build: Fix zip creation on Mac OSX

When checking if files are symbolic links, then ota_from_target_files
expect the permissions of the file to be 0755 which is always the case
on Linux, but not on Mac OSX. I adapted the function so that permissions
are not included in the check anymore. Instead it uses only the type
attributes of the zip external_attr flags.
CM uses the same kind of check.

Change-Id: I5d5d0567cb798b765cbc19a66661163f80e21f70
Fix utc date in recovery default.prop

We had this in Omni 4.3 but apparently it got lost during the
transition to 4.4

Change-Id: I09aed0e35eeeada3f3b998e69b3092741a745385
ota: Disable downgrade check

We want users to be able to downgrade their packages.

Change-Id: I6bcbd4ee2a02640fe0855b0f1f197a02e914c927