Hlookup

the following changes should fix the hlookup operator. I tested it on the latest Drill code, on a single node (embedded) with hbase and it's working fine.
which one ? 
the one that extract 'tableStr' and 'columnsStr' ?
basically, the attribute table is populated with the whole column from the secondary query, using buffer.start and buffer.end you can find wich bytes are relevant to the current row.
Why do I need to extract the strings here ? when I tried to pass table and columns to the helper, Drill complains that the signature of helper.lookup() doesn't pass with the passed attributes, probably because the code generation stuff changes those variable types depending on the query. With better knowledge I could probably find what types should be declared in lookup(), but in the meantime, this is just easier.