Add requested reviewers field to pull request records

[toddmohney]

From the GitHub Api docs

Deliveries for review_requested and review_request_removed events will have an additional field called requested_reviewers.

Adds simplePullRequestRequestedReviewers and pullRequestRequestedReviewers fields to SimplePullRequest and PullRequest respectively.

[toddmohney]

Hmm... couldn't seem to get the build to pass here without the update to the .travisci file. The changes are a result of running the travis encrypt command from the README and likely an undesirable change to merge into master.

The reason I ran the travis encrypt command was because of GitHub auth errors on my travis account where I have a fork of this repo. Any advice here?

[toddmohney]

Removing the .travisci file changes and trying again...