Add support for ability to start and stop IPFS via command `service ipfs on/off`.
Add support for `ProcessState.Errored` process state in the `ProcessManager`. This allows for processes being launched and stopped to trigger an error and the resulting process will be in an errored state. Processes in errored states can still attempt to be started and stopped.
`service ipfs on` - starts an IPFS node if not already started. Shows an error if the node is already starting or started.
`service ipfs off` - kills the running IPFS node as long as Embark has started the IPFS process. If the IPFS process was started externally, an error is shown.
return early
If a package uses only `.js` then supply `--extensions ".js"`. If a package
uses only `.ts` then supply `--extensions ".ts"`. If a package uses both, then
supply `--extensions ".js,.ts"`.
The reason for this is that adding/removing TS/JS support ought to occasion
revising a package's `package.json` file and adjusting other scripts as well,
e.g. for linting. With these changes, it won't work to simply start adding
`.ts` files in a package's `src/` directory, which should prompt the developer
to review `package.json` and make the appropriate changes, and/or other
developers may realize changes need to be made during code review.