Add L4LB resources to midonetclient

This patch adds resources specified in our L4LB specification to
midonetclient.

Signed-off-by: Taku Fukushima <tfukushima@midokura.com>
Add L4LB resources to MidonetApi and Application.

This patch adds the connections between the application and the L4LB
resources added by the previous patch.

Signed-off-by: Taku Fukushima <tfukushima@midokura.com>
Add the support of the L4LB feature to midonet-cli

This patch adds the commands for the L4LB featrue to midonet-cli.

Squashed tfukushima/python-midonetclient#1 submitted by @dcahill and
following patches.

Signed-off-by: Taku Fukushima <tfukushima@midokura.com>
Signed-off-by: Dave Cahill <dcahill@midokura.com>
Add doc/*.html to .gitignore

Signed-off-by: Taku Fukushima <tfukushima@midokura.com>
Change help texts of commands to docstrings.

Signed-off-by: Taku Fukushima <tfukushima@midokura.com>
Refactor midonet-cli to use the new style classes

`super()` is only supported in Python3 and I just put the class name and
`self` as an instance for the arguments of `__init__`. It's not
abstracted well but the follwing idiom doesn't work for the classes
which have further derived class because `self.__class__` would be
always the class of the instance `self` and cause the stack overflow.

    def __init__(self, obj):
        super(self.__class__, self).__init__(obj)

See the following links for the further information:

  * http://stackoverflow.com/questions/54867/
  * http://stackoverflow.com/questions/576169/
  * http://www.artima.com/weblogs/viewpost.jsp?thread=236275

Signed-off-by: Taku Fukushima <tfukushima@midokura.com>