Include the oauth setup URL in the error message

When the JIRA issue validation fails because there is no oauth token,
give the user the URL to use to create the trust relationship.

This is a much better user experience than telling the user to go and
find a commit in the web UI with a JIRA issue and click on it.
Detect when a JIRA oauth token is present but invalid

When an oauth token is present but invalid, throw an exception to behave
similarly to the token not being there at all, to allow for a proper error
message.

This has to be wrapped in a ResponseException so that the checked exceptions
for the ApplicationLinkResponseHandler interface contract is met.
Merge pull request #14 from bbaetz/show-url-on-jira-auth-failure

Include the oauth setup URL in the error message