Dockerfile: use the same version for armhf and amd64
Dockerfile: use the same version for armhf and amd64

Use node-7.1 for both platforms, as 7.1.4 isn't on armhf yet.

Signed-off-by: Sean Cross <d7e19930cc1f42c2d0781f4d9e6f1fe5891bf9cf@xobs.io>

chibitronics/ltc-webview-layer,chibitronics/ltc-webview-layer,chibitronics/ltc-webview-layer,chibitronics/ltc-webview-layer