Fix error in v3 credentials create/update

The v3 credentials passes data associated with the credential in
a "data" key, but the underlying API expects "blob", which is also
what is documented in the API spec.

Currently any attempt to create a credential with a type of 'ec2'
will fail with 'Invalid blob in credential' So s/data/blob to fix.

Change-Id: I0858e8c39653477eb554ee9d15fb4f2dde2b195c
Closes-Bug: #1259461
v3 test utils, don't modify input parameter

As mentioned in https://review.openstack.org/#/c/61046/ for
test_update, we should not modify the input req_ref in test_create
instead we should make a copy

Change-Id: I649433596a3ebbf2133eb724f09eb4bd470b7cdd
Whitelist external netaddr requirement

* tox.ini(testenv.install_command): Use the --allow-external and
--allow-insecure options so that pip 1.5 and later will assent to
retrieve the netaddr package even though it's not hosted on PyPI.
The --allow-insecure option is aliased to a clearer
--allow-unverified wording in 1.5, but the old form is being used to
avoid breaking users of 1.4.x and will be valid at least through
1.6.x according to comments in the pip source.

Change-Id: I7c29467ebdddee7a6c68ec3fd13579e4f0c40d30
Closes-Bug: #1266513
Co-Authored-By: Jeremy Stanley
Merge "Fix error in v3 credentials create/update"
Merge "v3 test utils, don't modify input parameter"
Merge "Whitelist external netaddr requirement"