Throw UnsupportedOperationException from unimplemented Neo4jStatement methods

Fix for #17. Neo4jStatement should not fail silently when methods are called which are currently not supported.

I've added code that throws UOE from every method where it was obvious to me. There some methods I'm not sure about:
* execute(String, int)
* execute(String, int[])
* execute(String, String[])
* executeUpdate(String)
* executeUpdate(String, int)
* executeUpdate(String, int[])
* executeUpdate(String, String[])
* isWrapperFor(Class<?>)
* getMoreResults()
* getMoreResults(int)
* unwrap(Class<T>)

These methods contain logic, but they don't look correct to me. For example all the execute methods delegate to execute(String) and ignore any additional parameters.
Ok, makes sense. The Javadoc states:

This indicates that the JDBC driver does not support an optional JDBC feature. Optional JDBC features can fall into the fallowing categories:

* no support for an optional feature
* no support for an optional overloaded method
* no support for an optional mode for a method. 

The mode for a method is determined based on constants passed as parameter values to a method