add support for Django-1.6

Sessions now store JSON instead of pickled objects.

Partially-implements blueprint django-1point6

Change-Id: I332ba18005284774a53fb3cb8c6e51bca1480ded
unify keypair name handling

CreateKeyPair and ImportKeypair handled name checks in a different
way. When importing a keypair, one got a generic error message
without a hint, that the name was wrong.

Change-Id: Ie82c0cd21f70aae3f55b84a1c05c9f170eaec312
Closes-Bug: #1265563
Merge "add support for Django-1.6"
Merge "unify keypair name handling"