add definition for the ROCKTAB keyword
fixed: keep a copy instead of a reference

storing string references are not a good idea, since temporaries are
often used. fixes RawRecordTest on my box
Merge pull request #233 from andlaus/add_ROCKTAB

add definition for the ROCKTAB keyword
Merge pull request #236 from akva2/no_references_for_you

fixed: keep a copy instead of a reference