Exception is its own type; exception has message

because exception and value are mutually exclusive.

Signed-off-by: Damien Le Berrigaud <damien@pivotallabs.com>
Agent responds with exception on unknown request

behavior parity with the ruby agent

Signed-off-by: Damien Le Berrigaud <damien@pivotallabs.com>
convert double to structs for cleaner assertions

Signed-off-by: Nick Wade <nwade@pivotallabs.com>
extract JobInstanceRenderer from ConfigurationHasher

Signed-off-by: Nick Wade <nwade@pivotallabs.com>