Include scope in AuthData
Improve logging in authStorage
Added table for api access tokens
Improve error report flow in oauth2 handler
Update schema of leejo_api_authdata

1. Scope and state should only be varchar(255). Long text should not
   be supported at all

2. Added redirect_uri to record the redirect_uri parameter in the
   request
Update authdata save and load

1. Added fields
2. Fix bug in LoadAuthorize method in authStorage
Added some quick hack for browser debug

Accept GET at the token endpoint.
Should be reverted when development is done.
Improve OAuth2 related tests

1. Added proper query parameters to authorize endpoint request
2. Added proper query parameters to token endpoint request
Added authdata delete to authStorage

A note that authdata storage is very temporary. It is best to do with
memcache-alike temp storage than harddisk based storage.
Separate data object from authStorage file
Define database struct for OAuth2 access data
Add create, retrieve and delete of access data

In authStorage, added logic to create, retrieve and delete access data