Fix pip failure when version is parsed as a float

##### Issue Type: Bugfix Pull Request
##### Ansible Version: 1.7 (8a6cfa1a)
##### Environment: N/A
##### Summary:
See #8108 for more details. Only applies if you're using YAML to specify module arguments instead of the more customary `k=v` format.
##### Steps To Reproduce:
```
- name: Install supervisor
  pip:
    name: supervisor
    version: 3.0
```
##### Expected Results:
`supervisord` should get installed
##### Actual Results:
```
line 153, in _get_full_name
    resp = name + '==' + version
TypeError: cannot concatenate 'str' and 'float' objects
```