OAuth 2.0 negotiation working using OAuth2Return web script
  - Script is successfully able to use OAuth2CredentialVaultProvider to
    store tokens against the endpoint ID of the OAuth-protected API
    (removed providerId field from script class)
  - OAuth2CredentialVaultProvider uses ConnectorService instance to
    retrieve the repo connector required to save values
  - Bean webscript.org.sharextras.slingshot.oauth2-return.get can now be
    extended for specific OAuth providers, provides connectorService
    reference on the parent
  - Added extra debug and suppressed warnings