Fixes #181 and #184 -- Clarified and cleaned up README.rst.

Note that I had problems with bower/grunt installation due to f'uped version of node.js. However, fixing doing the job "by hand" yielded positive results. Hope the restructured README is more helpful now.
Just tried it myself, but got the following error during `manage.py migrate`::

    FailedDryRun:  ! Error found during dry run of    '0015_auto__add_venueticket__add_simcardticket__add_supportticket__del_field'! Aborting.
    Traceback (most recent call last):
      File "/.../south/migration/migrators.py", line 170, in _run_migration
        migration_function()
      File "/.../south/migration/migrators.py", line 59, in <lambda>
        return (lambda: direction(orm))
      File "/.../djep/pyconde/attendees/migrations/0015_auto__add_venueticket__add_simcardticket__add_supportticket__del_field.py", line 51, in forwards
        self.gf('django.db.models.fields.related.ForeignKey')(default=orm['contenttypes.ContentType'].objects.get(app_label='attendees', model='venueticket').id, blank=False, to=orm['contenttypes.ContentType']),
      File "/.../south/orm.py", line 402, in __getattr__
        raise AttributeError("You are in a dry run, and cannot access the ORM.\nWrap ORM sections in 'if not db.dry_run:', or if the whole migration is only a data migration, set no_dry_run = True on the Migration class.")
    AttributeError: You are in a dry run, and cannot access the ORM.
    Wrap ORM sections in 'if not db.dry_run:', or if the whole migration is only a data migration, set no_dry_run = True on the Migration class.

Might be something wrong with my env?