Add datastore properties to OS::Trove::Instance

Latest Trove supports datastore type and datastore version options
when creating Trove instances. This patch enables their usage in Heat.

Change-Id: I1d037a9fbf66f13c3195a55c7325d19b5e9a058c
Closes-bug: #1257690
remove bogus comments re stack_delete_after in tests

We no longer use the stack_delete_after decorator, so move these old
comments referring to it

Change-Id: Ib7e9f190cdee3bc337542c1d61736c5fa530216c
Fix typo in HOT template guide

Under the "Template input parameters" section, there was a typo in the
following sentence:
"For example, the following definition for the instance_type parameter
would select the ‘m1.small’ flavor unless specified otherwise be the
user."

Closes-Bug: 1339269
Change-Id: I59a170407669c74d23f36b232b3d492e52ce5eac
Merge "Add datastore properties to OS::Trove::Instance"
Merge "Fix typo in HOT template guide"