Replaced ChaincodeStub with ChaincodeStubInterface to allow
unit testing of chaincode. MockStub added to emulate a real
chaincode without the storage or network requirements.
Unit test examples for chaincode_example02 to 05.

I have another changeset to address tables and certificates.

Change-Id: I37d6115781436e080a70d5c48c1128ee01fef3ba
Signed-off-by: Bradley Gorman <bgorman@au1.ibm.com>