Remove TO_DATE support from roadmap: It's already implemented

It's already implemented and working:
https://github.com/h2database/h2database/pull/150

Remove Java 6 backwards compatibility

Since we now require at least Java 6 we can remove the Java 6 backwards
compatibility layer.

Support byte[] in getObject

Add guards to JDBC debug code

The current implementation of getObject does not support byte[]. This
is an issue for some people [1].

 [1] https://groups.google.com/forum/#!topic/h2-database/InWprFw2B0o

Some of the existing JDBC code is missing guards around debug
statements that allocate strings.

Also build Java 8

To verify compatibility and for potential JSR-310 support
it would be good if we test against Java 8 as well.

fix compare TIMESTAMP WITH TIMEZONE

Added support to define last IDENTIFIER on a Trigger.

Tests for timestamps

since we no longer support jdk6

Implemented unit test.