Change ID column of Event table to UUID

If you are using a public Heat you can use the event ID in
'heat event-list' to measure how much activity the service provider
has in their heat installation.

To avoid this, the Id column of the Event table was changed from
autoincremental integer to a uuid.

Added some unit tests in order to ensure that events with integer or
uuid id pass through the API, since we have a migration which will
leave behind integer ids.

Change-Id: Ib3eddb700738cb3667c72977a9a5011209acd6d7
Closes-Bug: #1249159
Fix regression in cloud server tests

Commit 116bd3cb13d76f61fe779b55d5591da671ae471b broke the cloud server contrib
tests because they mocked the default Clients calls instead of the resource's
nova function. This patch adds the correct mocks to the cloud servers tests.

Closes-Bug: #1257947

Change-Id: I904eb9f7e6424603d42b0d59c44e4da16726368c
Account for truncated resource names in test PhysName

The utility class PhysName was blindly comparing resource
name without considering that the resource name may
have also been truncated.

Closes-Bug: #1251379

Change-Id: I189f79ee5238b7c82eff1595ef612efb1f8633d4
Make build_userdata user_data_format aware

Over time different user_data_format values could assemble
different combinations of cloud-init parts.

As the default will remain user_data_format='HEAT_CFNTOOLS',
identical content will be generated for the Instance resource.

The Server resource now passes user_data_format, and no longer
has a get_mime_string method since build_userdata is only ever
called once so cached get_mime_string results is not needed.
Change-Id: I7cfbcffeea24c9b1f013463f9a5fa53b8c699cfe
Instance call build_userdata directly

get_mime_string is only ever called once so caching the results
in self.mime_string is not necessary.

Change-Id: I36a1eb358b1228a946c5f8fa6e76869f10c398fd
Allow intrinsic functions to be called in any order

An optional transform function can be passed into the resolve
functions, which allows transforms to occur on the child snippets.

Change-Id: I5d9e061c6a55f3939c5e03c780eaad72a001fccc
Closes-Bug: #1256742
Merge "Fix regression in cloud server tests"
Merge "Account for truncated resource names in test PhysName"
Merge "Make build_userdata user_data_format aware"
Merge "Instance call build_userdata directly"
Merge "Change ID column of Event table to UUID"
Merge "Allow intrinsic functions to be called in any order"