Remove "http_valid" attribute from valid_http_credentials

[Griffin-Sullivan]

valid_http_credentials function in datafactory.py has an attribute for http_valid. However, there is an invalid_http_credentials function in datafactory.py that is for returning invalid http credentials. valid_http_credentials should only have http valid credentials and we should move any of the invalid credentials into invalid_http_credentials.

This would also require some manipulating of any tests using these functions, as currently anyone who wants only valid HTTP credentials has to use

for cred in valid_http_credentials():
if cred['http_valid']