FoundationDB SQL Layer adapter

This PR adds support for the [Foundation DB SQL Layer](https://foundationdb.com/layers/sql). The new adapter works both with jdbc and on its own. 

As far as the integration tests are concerned all that are not ignored in this PR are passing. Occasionally one or two tests will fail because the transaction takes too long, rerunning fixes it. It requires the latest SQL Layer (v2.0.0).