This squashed changeset does the following:
 - It renames UUID to TXID in the code (Go/Java), in tests,
   in proto files, in all chaincode related files
 - It uses all the arguments of the chaincode to
   generate the TXID

Change-Id: Iae6f1fb45c12c2652d9ad18451e75ea1f91fe9a3
Signed-off-by: Gabor Hosszu <gabor@digitalasset.com>