Updates on consume_test, produce_test, and Consumer.js

updates

in consume_test.js
multiple options object creates confusion. Removed one.

in produce_test.js
currently the producer was throwing "error undefined" with each message sent to kafka. code was edited to log errors only if error is defined.

in lib/Consumer.js
If we are passing offset 0 with options passed to consumer, the offset never gets reset to 0 but instead sets to last offset due to the if(options.offset) check done. So the condition was edited accordingly.