Give friendly notification in swift-get-nodes

Hard coding of '/srv/node' maybe drive to some errors. But it seems
unfixable (please see talks in bug report). To avoid erros as we can,
showing a friendly notification to let user set their own device
location works better than hard coding directly.

Change-Id: I45d749dd52af8d3b051dfe98dbb9d71a5a374f97
Fixes: bug #907908
Merge "Give friendly notification in swift-get-nodes"