Improve MaxCtrl test coverage

Added tests that cover areas that weren't tested before.

maxctrl/test/drain.js

@@ -0,0 +1,19 @@
+require('../test_utils.js')()
+
+describe("Draining servers", function() {
+    before(startMaxScale)
+
+    it('drains server', function() {
+        return doCommand('drain server server1')
+            .should.be.fulfilled
+    })
+
+    it('checks server is in maintenance', function() {
+        // The maintenance state isn't set instantly
+        return sleepFor(2000)
+            .then(() => doCommand('api get servers/server1 data.attributes.state'))
+            .should.eventually.have.string("Maintenance")
+    })
+
+    after(stopMaxScale)
+});