UK SSO: Multiple code style and documentation improvements.

#### What's this PR do?
- Refactors Dosomething UK module: multiple code style and documentation improvements

#### How should this be manually tested?
- Enable and setup Dosomething UK module
- Run `ds test uk`  
  ![image](https://cloud.githubusercontent.com/assets/672669/4567462/4d7eca80-4f31-11e4-9275-5278aba96334.png)


#### What are the relevant tickets?
Closes [#DS-377](https://jira.dosomething.org/browse/DS-377).