ota: Remove cruft we don't care about

Skip the date check (downgrade to your content), and don't include
recovery in otapackages.
fix up ota_from_target_files symlink detection.
Add otapackage support for backuptool

Change-Id: I512554c579d444067cd3ccbb0e6946a5eb6bc964a

Conflicts:
	core/Makefile
Allow override of device asserts, including multi-device support.

Set in board file with TARGET_OTA_ASSERT_DEVICE.
(cherry-picked from commit 0f452f21fc9323b9d1fe746161761cf40aaa5030)

Change-Id: I3d06bdc0e3e26bde0c0e646accd050364f9713b9
build: Support nam configuration script in ota package

Similar to the --backup command that allows adding the backup and
restore script, this allows the use of --configid to append the
modelid_cfg script below the backuptool, as previously configured in
CM7 builds.
This adds support for devices that originate from other countries, but
have a North American counterpart that requires alternate GPS and sound
profiles.
Unlike backup tool, which uses the cm prefix to an existing lunch combo
variable, this flag can apply to devices not currently supported by CM.
The supported devices are manufactured by HTC, so instead of verifying
a cm prefix, the htc_ component is used to trigger the append.

Conflicts:
	core/Makefile
	envsetup.sh
build: Cleanup nam configuration and enable by default

Removed unnecessary conditional for non-ota packages. Integrated checks
to make sure NAM_VARIANT did not override CM_BUILD and CM_BUILD did not
override NAM_VARIANT.
Added to all cm builds, since the script will be available and will not
interfere with devices that do not need it, but also to all htc
devices, which will usually need it.
Enabled the script by default, since it will not hurt devices that do
not require the configuration.

Conflicts:
	core/Makefile
	envsetup.sh
update ota_from_target_files to handle mounting/unmounting for backupscript

backupscript should not be mounting/unmounting itself as it makes other
scripts have unexpected results (such as modelid_cfg, which expects /system
to be mounted)

instead have the ota script handle the mounting/unmounting

Change-Id: I94511f4147c624d975cb3ecbeaa8b0e98f63437c