improve OTA failure messages

Replace OTA script constructs of the form:

   assert(foo);

with

   foo || abort("sensible message");

so that the log and the on-screen display is somewhat more accessible
to non-experts.  (assert() displays the source code of the false
expression 'foo'.)

Change-Id: Ic99448e4466561d305b167cd4d5c1f0f2dbadcce
Fix up the recovery.fstab for adv recovery

Add options found in cm7 to allow for more complex recovery.fstabs with
multiple fstypes.

Change-Id: Id249c8f6766a1490a80fb3bd17bd7aa4e7dd9f2f
fix up ota_from_target_files symlink detection.
Remove build.date.utc assert check

Signed-off-by: Brandon McAnsh <brandonm@matricom.net>
CWR does not support writing a partition from memory. Use /tmp to store the extracted file, then write it.
Add ext2, ext3, and vfat to releasetools

Support some non-standard partition that may be found in recovery.fstab

Change-Id: I0026a1d3ae5d432db10150d1a15f7bc8e7a6054b

Signed-off-by: Brandon McAnsh <brandonm@matricom.net>
Allow disabling DroidDoc build

Signed-off-by: Brandon McAnsh <brandonm@matricom.net>