Handle quoting of values in dict parameters

In https://github.com/ansible/ansible-modules-core/issues/543 the user is trying to set a dictionary parameter via a string (non-complex args syntax).  This is failing because the value contains a comma inside of quotes and the naive parsing of the parameter thinks that the comma is a dictionary field separator.

This will fix that.  As a side effect it also allows space to be a separator, not just comma.  For example the new code should do this:

```
in a playbook:
ex_dictionary: a='test' b='test,test_b',c='foo bar',    d='yep, "this" too'
==>
inside the module:
ex_dictionary == {'a': 'test', 'b': 'test,test_b', 'c': 'foo bar', 'd': 'yep, "this" too'}
```