Re-enable disabled tests once automated setup is possible

[HowardWolosky]

The following tests have been disabled (in GitHubAnalytics.tests.ps1):

• Obtaining pull requests for repository
• Obtaining repository with biggest number of pull requests
• Obtaining organization members
• Obtaining organization team
• Obtaining organization team members

They've been disabled because the module does not yet have the functionality to get the test repository into the necessary state for testing (e.g. it needs to be able to create and delete pull requests, create teams and members, etc...).

Once the necessary functionality has been added to the module, those tests should be re-enabled and this issue can be closed out.