Remove support for `service whisper on/off` because Whisper cannot be started without first disabling it in the communications config, then restarting Embark.
Add documentation for the `service [process] on/off` command
This command was only added a few commits back so it is not considered a breaking change.
Refactor the `service [process] on/off` commands so that there is only one command. Previously we had a command registered for each process, ie:
```
service blockchain on/off
service ipfs on/off
…
```
Now, we only have one command with many options:
```
service [process] on/off - Starts/stops the process. Options: blockchain, embark, ipfs, api
```
Whisper is deliberately not included in the available options for the aforementioned reasons.
Michael Bradley, Jr
Jonathan Rainville
Pascal Precht
emizzle
yanqian
Sebastian Mueller