Mujina now support attributes with multiple values.

As per spec attributes should be able to contain multiple values. E.g.

"urn:mace:dir:attribute-def:eduPersonEntitlement": [
  "urn:mace:terena.org:tcs:personal-user",
  "urn:mace:terena.org:tcs:personal-admin"
]

This changes the API in such a way that from now on you ALWAYS need to
PUT attributes in an array as follows {"value": ["value1"]}.
Merge pull request #3 from OpenConext/make-attribute-multivalue

Mujina now support attributes with multiple values.