JOhm error dictionary (patches issue 27)

[gsharma]

Created JOhm error dictionary and exposed to clients to allow them to plan appropriate responses based on error metadata (patches issue 27). This change also does not break any client interface since JOhmException's getMessage() is enhanced and a new getMeta() exposed on the class.

[gsharma]

Upgraded to Jedis v2 and includes some other patches.