Add status command

closes #1471 by adding the status command that prints the state of a
machine.

Signed-off-by: Sergio Botero <sergiobuj@gmail.com>

docs/reference/index.md

@@ -27,6 +27,7 @@ parent="smn_machine_ref"
 * [scp](scp.md)
 * [ssh](ssh.md)
 * [start](start.md)
+* [status](status.md)
 * [stop](stop.md)
 * [upgrade](upgrade.md)
-* [url](url.md)
+* [url](url.md)

docs/reference/status.md

@@ -0,0 +1,18 @@
+<!--[metadata]>
++++
+title = "status"
+description = "Get the status of a machine"
+keywords = ["machine, status, subcommand"]
+[menu.main]
+parent="smn_machine_subcmds"
++++
+<![end-metadata]-->
+
+# status
+
+Get the status of a machine.
+
+```
+$ docker-machine status dev
+Running
+```