updates for 3.5, null terminated some strings

Patch mostly adds support for latest 3.5 BlockBasedTableOptions which
deprecates some normal options.

Also found that stringToChar() is not properly null terminating strings.
Not all uses are fixed, mostly because the ones remaining are tricky.
This was causing some issues in opening the database mostly, the
directory would change names on occasion and start fresh. Relevant issue
here: https://github.com/facebook/rocksdb/issues/332#issuecomment-57893418

couple files got caught by gofmt, if that bothers you I will gladly
remove them from the patch and resubmit.