Herron

Fixes several edge cases around offset parsing. The following are supported now:

-1-           This will start consuming at the latest offset for all partitions
-1:100-       This will start consuming at offset 100 for all partitions
-1:30-,5:40-  This will start consuming at offset 30 for all partitions except 5 for which it will start at offset 40.

Internal:

• Adds setup for testing consume functionality more thoroughly.