56: Completed (mostly) refactoring work for Helpers

* Added IssueHelper interface with primary API for what the BZ and JiraHelpers have to be able to do. The API is:

```java
Issue findIssue (URL url);
boolean accepts(URL url);
boolean updateStatus(URL url, Enum status);
```

* The status implemetations are not done yet, and have to be thought out in more detail. They currently just thrown UnsupportedOperationExceptions.

* The constructor for the RedhatPullRequest was updated. It takes three parameters. Two IssueHelpers and one GithubHelper.

* Renamed JiraHelperTest to JiraIssueTest. Since that is more appropriate to what the test is doing.

* Introduced Mockito as a framework for writing Mock objects for testing purposes. We'll use this in other issues for testing, that way we don't have to configure credentials for making remote calls to JIRA and BZ

* Removed Mock* classes as they are not needed anymore.

* Assertions are made with testng, and not AsserJUnit.

* I know that there are FIXME's introduced into this PR. There are separate issues for them to be cleaned out.