Fix ziploader for the cornercase of ansible invoking ansible.

* Make ziploader's ansible and ansible.module_utils libraries into
  namespace packages.
* Move __version__ and __author__ from ansible/__init__ to
  ansible/release.py.  This is because namespace packages only load one
  __init__.py.  If that is not the __init__.py with the author and
  version info then those won't be available.
* In ziplaoder, move the version ito ANSIBLE_CONSTANTS.
* Change PluginLoader to properly construct the path to the plugins even
  when namespace packages are present.

lib/ansible/module_utils/__init__.py

@@ -15,3 +15,6 @@
 # You should have received a copy of the GNU General Public License
 # along with Ansible.  If not, see <http://www.gnu.org/licenses/>.
 
+# Note: Do not add any code to this file.  module_utils may be a namespace
+# package when using Ansible-2.1+ Anything in this file may not be available
+# if one of the other packages in the namespace is loaded first.

lib/ansible/module_utils/basic.py

@@ -219,10 +219,6 @@ except ImportError:
 
 _literal_eval = literal_eval
 
-from ansible import __version__
-# Backwards compat. New code should just import and use __version__
-ANSIBLE_VERSION = __version__
-
 # Internal global holding passed in params and constants.  This is consulted
 # in case multiple AnsibleModules are created.  Otherwise each AnsibleModule
 # would attempt to read from stdin.  Other code should not use this directly

lib/ansible/module_utils/rax.py

@@ -32,7 +32,6 @@ import os
 import re
 from uuid import UUID
 
-from ansible import __version__
 from ansible.module_utils.basic import BOOLEANS
 
 FINAL_STATUSES = ('ACTIVE', 'ERROR')
@@ -264,7 +263,7 @@ def rax_required_together():
 
 def setup_rax_module(module, rax_module, region_required=True):
     """Set up pyrax in a standard way for all modules"""
-    rax_module.USER_AGENT = 'ansible/%s %s' % (__version__,
+    rax_module.USER_AGENT = 'ansible/%s %s' % (module.constants['ANSIBLE_VERSION'],
                                                rax_module.USER_AGENT)
 
     api_key = module.params.get('api_key')