Refactor and add tests around REST api workloads
Merge pull request #49 from knolleary/master

Add workload options to README.md
Merge branch 'master' into restapirefactor
Add a default workload
Add list-workloads option
Reject invalid workloads
Move workload list to its own thing
Merge pull request #51 from julz/reject-invalid-workload

Reject invalid workloads, and List available workloads
cmdline honours csvDir parameter
Redis store
Redis store has connection parameters
Store type can be configured with flags or config
Config.go supports environment variables
Config allows double-binding when safe
It configures REDIS store with VCAP_SERVICES
Redis supports passwordless connections
fix travis
Workload Steps have an optional context parameter

Fixes the previously non-concurrency safe way of sharing state between
workload steps. Now a workload step can specifically ask for a context
map which is created before and passed between each workload step.
Rest workloads use context
Tidy up