Fixed several sql adapter bugs

* exception handling in initialize
* add pepper only if it exists
* only access token if it exists
Added sql adapter tests

Currently there are only a view, yet. We should wait for
creating more until we merged diaspora/vines#13

refs diaspora/vines#14
Using Rails for database access instead of AppConfig
Updated README.md
Merge pull request #15 from Zauberstuhl/add_sql_adapter_tests

Add sql adapter tests
Add non diaspora contacts to your roster

It is now possible subscribing to normal jabber addresses