Small cleanups, simplification and removed no longer needed cast

Enhancement: expose ping() on pingable-connections.

 * license
 * author tags
 * doc blocks
 * new lines

 * h/t @stof and @deeky666
 * add two test cases for the general connection test
 * remove the ConnectionException method I added originally

Implement SQL Anywhere driver exception conversion

Add SQL Anywhere configuration documentation

Skip unsupported tests on SQL Anywhere

This PR introduces a new PingableConnection interface and exposes
a ping method on \Doctrine\DBAL\Connection. For drivers where no
ping is supported, a \Doctrine\DBAL\ConnectionException is thrown.