Added details on how to build with Gradle.
Retrieve body of response even if there's an error.
Sometimes error details can be returned which can be used.
Add strings for use in new authentication process.
Update authenticator layout to collect user/password.
Use OAuth client credentials flow to authenticate.
JIRest class should be public.
Layout tweaks, remove token text.
Use correct username stored against account.
Adjust OAuth configuration doc re. new changes.
Rename oauth file property to "client_id".