Cleans up the l3 agent manifest

This patch makes the following changes to the l3 agent manifest:

  * Adds a doc header
  * Removes the auth parameters as they are no longer used
  * Removes the metadata IP parameter as its no longer used
  * Sets router and gateway IDs to undef values
  * Adds a parameter to use OVS to create the external bridge
  * Adds some tests

Change-Id: Ia36141fdb9433c629c7945cc1774b549bdff4c69
Changes the server manifest

This patch changes the server.pp manifest:

  * Adds a doc header
  * Sets auth_password to false so noauth can be used
  * Wraps the auth stuff into a conditional block so noauth can be used
  * Formatting cleanup

Change-Id: Ia6e4522c5b45c5c4b59becae70d7468757a79f6a