Modify generate_methods to accept predefined alias

This patch modifies generate_methods to accept predefined
aliases of the API handlers. Previously it uses the first Camel
or Camel_snake cases in the class name and it does now, but it
also supports the predefined ALIAS attribute in the class
definition and use it to generate methods over its class name.

Change-Id: I1480d839a68359c84704ab7bdfcb0c3502b70f0b
Signed-off-by: Taku Fukushima <tfukushima@midokura.com>
Add API handlers of BGPs to MidonetPluginV2

This patchs adds the API handlers of BGPs and AdRoutes to the
core plugin with some additional tests.

Change-Id: I5b26a80648617f45c9b2bf0c57fe989644c3c378
Signed-off-by: Taku Fukushima <tfukushima@midokura.com>
Add API hendlers for chains and ruels to MiodnetPluginV2

This patch adds API handler mixin for chains and rules to
MidonetPluinV2 with the unit test of the POST requests.

Change-Id: Id7f87a815aa0c1eaed60656e60e01b4215dfd18f
Signed-off-by: Taku Fukushima <tfukushima@midokura.com>