tests: disable crash reporter unit tests, it tends to crash.
payloads: remove original signing key version

OrignalVersion was only used to generate a warning when creating a
update payload and mis-used in a couple tests. The warning is just going
to be hidden under a couple layers of scripts (delta_generator's usage
is far too terrible for anyone to use it by hand) so the warning is
unlikely to serve any use and would just contribute noise while
generating updates with dev keys which only need a single version.
payload_signer: update to signature version two

Do a key rotation and have the update engine use keyslot 2.
delta_performer: disable metadata verification

metadata verification has no method for doing key-rotation of the
payload. Since it is designed primarily to protect against a man in the
middle attacker disable it for now until we can come up with a
key-rotation strategy.
delta_performer: continue to validate operation hashes

Checking the install operation hashes is skipped if the metadata
signature is not provided to support some transition in ChromeOS. This
does not apply to CoreOS and metadata signature is going away for now
but it doesn't hurt to continue to check other hashes.
delta_generator: remove support for writing metadata signatures
cleanup: remove remaining references to metadata signatures.

The functional code related to metadata signatures is gone now, this
expunges the lingering support code. Mostly it is just a lot of glue
passing the value from one data structure to the next.
Merge pull request #35 from marineam/version2

Update key version to 2