implemented jdbcoutputformat

Here's the implementation of the JDBC outputformat ( issue https://github.com/stratosphere/stratosphere/issues/261 ).

Arguments that have to be passed via the configuration:
* database url
* username and password (if not contained in the url)
* jdbc driver
* insert query
* the types of the columns in order. 

The configuration is constructed using a configbuilder. The target table is assumed to exist already.

The test file covers the functionality of the format by copying the contents of a table to another.
i added an example file showing both jdbc formats.