added a new builtin command "_getAllBytes" in order to retrieve complete
chunks across name spaces (which permits to verify the signature instead
of getting the content only). Example:

% ./util/ccn-lite-peek -s 1 "" \
"_getAllBytes(_getFromNameSpace 'ccnb /ccnx/0.7.1/doc/technical/sync.xsd.txt)"\
| ./util/ccn-lite-pktdump -f 2 | ./util/ccn-lite-pktdump

The first pktdump extracts the content from the ccntlv packet.
This is a full ccnb packet and is parsed by the second pktdump.