Could not start device session when devices are disconnected

[miroslavaivanova]

Environment
Provide version numbers for the following components (information can be retrieved by running tns info in your project folder or by inspecting the package.json of the project):

• CLI: 6.1.0

Describe the bug
Your device is connected with USB and WiFi. If you disconnect it from Wifi and USB and make a change, you will see error:
Unable to apply changes for device: d97ff43f5d13677a2fb09fc9b4da3066464ff5f4. Error is: Could not start device session.

To Reproduce

1. tns create app --js
2. tns test init
3. tns test ios
4. disconnect device from USB nad WiFi and make a change. You will see exception.

Expected behavior
should continue to work