Add receptorctl support for runtime parameters.

[shanemcd]

Per conversation with @ghjm. There is currently no way to send additional command parameters at runtime like there is when using the raw socket interface.

[squidboylan]

I tested this manually by starting a node:

---
- node:
    id: foo

- control-service:
    service: control
    filename: /tmp/foo.sock

- tcp-listener:
    port: 2223

- work-command:
    worktype: echo
    command: echo
    params: foo
    allowruntimeparams: true

starting a job:

(venv2) squid@localhost:~/work/project-receptor/receptor$ export RECEPTORCTL_SOCKET=/tmp/foo.sock
(venv2) squid@localhost:~/work/project-receptor/receptor$ receptorctl work submit echo these are extra runtime params --no-payload
Result:  Job Started
Unit ID: nhOU45Lb

and gathering the results:

(venv2) squid@localhost:~/work/project-receptor/receptor$ receptorctl work results nhOU45Lb
foo these are extra runtime params

works as intended