Add ability to configure policy_files_path and policy_files

This change adds the ability to configure policy_files_path
and policy_files configs used by the policy enforcement (RBAC)
support in Horizon.

Closes-bug: #1383458
Change-Id: Iad33e68d09b81b384d4333ef9fa785939d43f9e6
Switch to metadata.json for Puppet forge releases

Since puppet 3.x, Puppet Labs Forge accept only the metadata.json file
for module description (Modulefile is now deprecated).

This patch :
 - convert the Modulefile to metadata.json.
 - bump major version to 5 (for juno).
 - switch to stackforge namespace.
 - relax pe version_requirement to 3.x.

Change-Id: I195a4ebd7d8a9fe77f1ad7149fba6037f9e1a865
Merge "Switch to metadata.json for Puppet forge releases"
Add selection of Django session engine to this module

This allows Django to be set to use something other than
the default session engine through Puppet. By default,
it will have no impact on existing configurations.

We've added this because our security constraints make signed cookies
as a session store for Horizon undesirable. The reasons for this are:

  * Sessions become vulnerable to replay attacks,
    a clean log-out is difficult to achieve.
  * Serializing sessions in cookies may allow an attacker
    to escalate read-only access to server configuration
    into code execution via deserialization of attacker-generated
    content.

Change-Id: Iaf80bdc1bb9ce55ff46b2dcfac73daad90fd0d37
Merge "Add selection of Django session engine to this module"