DB-Driver: Add option to automaticly install driver from external source

With the transition to the apache foundation it gets more difficult to bundle arbitrary libraries.

In this case the libraries are JDBC drivers. For example the mysql JDBC driver had to be removed from distribution as the apache foundation won't redistribute binaries with licenses more restrictive, that the ALv2.

With only one remaining bundle driver (postgresql) the bundled functionality is mostly useless. So the process need to be improved: A rough outline:

• add a driver template mechanism to netbeans
• a driver template holds the information about a driver and the source
• applying the template would request the user if he wants to download the driver and requires the user to agree that the driver is not covered by the same license as netbeans itself
• the downloaded jars will be placed in the userdir and the drivers reference these

The primary source for the drivers should be maven central, as many vendors (including non-OSS) drivers are are present there:

For the maven based installers the license information can be extracted from the pom.xml and displayed to the user when installing other sources will need different approaches.