15. core: Add internal authenticator

This patch adds an internal authenticator based on the new
authentication interfaces previously introduced. This authenticator
behaves exactly like the previous one, taking the user name and password
from the AdminUser and AdminPassword configuration parameters stored in
the database

Currently, no conf file is needed.
In the future, we might consider creating an internal.conf file at
/etc/ovirt-engine/auth.conf.dd directory with the following content:

  #
  # The name of the authentication profile (this is what will be
  # displayed in the login form):
  #
  name=internal

  #
  # The name of the module containing the implementations of the
  # authenticator and directory:
  #
  module=org.ovirt.engine.core.authentication

  #
  # The types of the authenticator and the directory:
  #
  type=internal

This patch concludes a series of patches, due to jenkins infra issues
we had to manually run findbugs, rpm build & install and unit tests/dao tests to
confirm nothing breaks

Change-Id: I005e7e721b6342b292cf79ccf1e0355c65bd116f
Signed-off-by: Juan Hernandez <juan.hernandez@redhat.com>