Remove Authorize/Reauthorize options in settings

[dstillman]

There's no reason for people to authorize the connector before they try to save without the desktop app open. You should be able to unauthorize from the prefs, but you don't need to trigger that ahead of time. No need for the Reauthorize button either — you can just clear and trigger again. (And, currently, it leads people to do confused things.

For the unauthorized state, we should remove the Authorize button and change the line to "Zotero Connector is not currently authorized to save items to zotero.org. You will be prompted for authorization if you try to save items while Zotero is not open."