SdkTool: Support adding kit for desktop device

Change-Id: Ibaba86dd72655ec3734a7564ae9eec6c3c85df1f
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>
SdkTool: Use Qt Creator doctypes

Simplify filename conversion while at it

Change-Id: I0a7473aa42626a04214887f1cc82abe536233a78
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>