Fix Keypair exception messages

`InvalidKeyPair` exceptions weren't raising the
proper error message. The reason was that the
error message was passed in as an `explanation`
keyword which isn't understood by `NovaException`,
and so is thrown away.

This is part of a patch set to improve keypair
error message reporting in both the Openstack and
EC2 APIs.

References bug 1187952
Change-Id: Ide319cb126955927d623972dffd573cd4c4314df
Improve Keypair error messages in osapi

The KeypairAPI code provides useful error messages that weren't being
percolated back through the OpenStack API. This patch addresses this by using
the original `message` when crafting the HTTPException objects.

References bug 1187952

Change-Id: I786a225010d912d7bfea5c01838ddcf43fd90d53
More KeypairAPI cleanups

* DRY up quota checking for new keys

* DRY up formatting of get_key/get_all_keys results

* Add tests for get all keypairs

Change-Id: I14a97c0f3cb3aa9b827d14002c21076a41942023
Speeding up scheduler tests

Database access is costly in tests and many tests
don't actually need it. This patch provides a
simple way we can speed up the Nova tests by
providing a new base class, `NoDBTestCase` which
allows us to white-list tests not needing database
access.

The following speedups were observed:

    With TestCase:     Ran 265 tests in 17.080s
    With NoDBTestCase: Ran 265 tests in  9.478s

Further optimizaton could be done by fixing
`test_host_filters` to not hit the database. This
will require some effort though in order to
maintain the quality of test coverage since part
of what's doing is testing the code in the DB
layer.

Change-Id: Ic34c4c39d7f680ac501efb459fdeaa51331ffe1c
Added verbose error message in tests helper mixin

blueprint db-api-tests

Change-Id: I2fcfc50824de8965fe8521cde5f20d24e88eb8ae
Merge "Fix Keypair exception messages"
Merge "Improve Keypair error messages in osapi"
Merge "More KeypairAPI cleanups"
Merge "Speeding up scheduler tests"
Merge "Added verbose error message in tests helper mixin"
Merge remote-tracking branch 'm_src_repo/citrix-fixes' into build-temp