Add adapter name to a field in the connection object returned by createConnection()

The reason is really quite simple, and basically already encountered in your test suite: in order to write reasonably DB-abstract code, you sometimes need to produce different queries depending on the adapter used, e.g. for auto_increment/autoincrement, etc.

Since you accept (as per documentation) only connection URIs, not connection objects, the only way to find out which adapter is used is to either parse or construct the connection URI outside of any-db. You're parsing up URI already, though, so that seems a little redundant.