Provide :Homestead command

[noahfrederick]

Adds a :Homestead command for interacting with the Homestead VM from Vim's command line.

:Homestead {cmd}                                                  *:Homestead*
  Invoke shell {cmd} on the Homestead VM over SSH.

  Several strategies are tried for executing the ssh command in order:

    * Dispatch's |:Start| command
    * The built-in |:terminal|
    * At Vim's command line via |:!|

  The {cmd} is executed with the working directory being the project's
  directory on the VM. The project's directory is detected from your
  Homestead.json configuration file, using the "folders" mappings to do the
  translation from host path to guest path:
>
      "folders": [
          {
              "map": "~/code",
              "to": "/home/vagrant/code"
          }
      ],
<

  The plug-in will look for the Homestead.json file in the directory specified
  in |g:laravel_homestead_dir| or in ~/Homestead.

  Note: Only Homestead.json is taken into account, and not Homestead.yaml,
  since Vim cannot parse YAML. If you prefer to use the Homestead.yaml file,
  it's sufficient to set only the "folders" array in Homestead.json.


:Homestead
  Start an interactive SSH session on the Homestead VM.


:Homestead! [arguments]
  Invoke Vagrant with [arguments] in the context of the Homestead directory on
  the host machine. For example, to start the VM:
>
      :Homestead! up
<