Fixed 'Unknown sdkid' error in dashboard

Steps to reproduce problem:
 - open XDS dashboard,
 - display SDKs page list (click on SDKs in the left panel)
 - display Build page (click on Build in the left panel)
 - keep selected Project and SDK and just click on Build button
 - error 'Unknown sdkid' must be displayed

Problem partially comes from the fact that default/current sdk in
sdk.service is the first sdk and not the first Installed sdk.

Change-Id: I21b9310e8ad67ff71afb5b704b39f5f98bc8707b
Signed-off-by: Sebastien Douheret <sebastien.douheret@iot.bzh>