rangeReverse, SerializingSerde and AutoClosingTableIterator

Hi,

here the changes for the pull request. You will need to create the implementation for TreeMap yourself and move the test cases from ezdb-leveldb-jni into the common test class.

For the Testcase I also had to add my SerializingSerde which I am using as a replacement for all of your Serde-Implementations. You might consider making SerializingSerde the default and just allow the users to customize that with their own Serde-Implementations.

Also I've added my AutoClosingTableIterator fix which prevents some jvm crashes with leveldb-jni when using table iterators beyond what they offer for iteration (calling next() after hasNext() returned false). Also this helps users who can't (e.g. using Iterator directly as a wrapper) or forget to call close() each time.

Also I had to upgrade leveldb-jni from 1.5 to 1.7 in order to fix a lot of jvm crashes and inconsistent behaviour in my testcase.

Best regards,
subes