Add BSD license to module_utils/gce.py

* Adds another module utility file which generalizes the
  access of urls via the urllib* libraries.
* Adds a new spec generator for common arguments.
* Makes the user-agent string configurable.

Fixes #6211

* Adds another module utility file which generalizes the
  access of urls via the urllib* libraries.
* Adds a new spec generator for common arguments.
* Makes the user-agent string configurable.

Fixes #6211

Fixes #6331

tags lists are properly uniqued and joined now, also avoids type issues when passed as list/set or strings

Signed-off-by: Brian Coca <briancoca+ansible@gmail.com>

Fixes #6047

  failed: [127.0.0.1] => {"failed": true, "parsed": false}
  invalid output was: Traceback (most recent call last):
    File "/tmp/ansible-tmp-1393950384.39-102240090845592/nova_compute", line 1328, in <module>
      main()
    File "/tmp/ansible-tmp-1393950384.39-102240090845592/nova_compute", line 241, in main
      except exc.Unauthorized, e:
  NameError: global name 'exc' is not defined

This prevents a traceback when the group is empty.
Fixes #6258

Fixes #5305

Fixed missing ansible.errors import in assert module

Add option to enable the sysctl -e option

fix missing stdin in _parallel_runner

Tested with GIST https://gist.github.com/risaacson/7290d30a612e0c70ea1b.
Passes "make tests"
Passes non_destructive tests.

Don't lstrip data to be parsed by parse_yaml. Fixes #6384