Add ``inviter`` module to batch invite users.

https://github.com/madewithbytes/us_ignite/issues/18

The importer receives a list of touples containing
``name`` and ``email.

This will create a user and profile for them based
on these details using the same procedures as
``browserid``.

Refers #18.
Add form to import users in batches.

https://github.com/madewithbytes/us_ignite/issues/18

The form receives a payload with the ``user`` field
listing a new user on each line with the following format::

    name, email

The form validates every entry and removes any blank lines.

During the ``clean_users`` method the form will transform
the payload in a list of tuples containing the name and email.

Refers #18.
Update admin branding.
Provide mechanics to invite users in batches.

https://github.com/madewithbytes/us_ignite/issues/18

An admin form is available to import users in batch,
the format of the field must be a new line for
each user and each user should be in the following
format::

    name, email

It will use similar mechanics to ``browserid`` to
create and invite the users.

Closes #18.