feat(input-redis): implement optional redis blpop input
feat(output-redis): implement optional redis rpush output
doc(redis-input/output): doc for redis RPUSH/BLPOP
fix(input-redis): fix blpop queuing
Merge remote-tracking branch 'perrinood/feat-redis-rpush-blpop'

Conflicts:
	lib/inputs/input_redis.js
	lib/outputs/output_redis.js
Use bloop by default, and track redis config error
Code organization
@perrinood Some improvement in blpop management