You will need Visual Studio 2017 and dotnet-1.1.1-sdk (1.1.1 with SDK 1.0.1).
Note that you can install multiple SDKs side by side, it's all controlled through the global.json.
To build from the command line you will need NodeJS (Tested with 4.1) and Gulp installed.
To get the web UI to build, in Visual Studio, open the Task Runner Explorer and run the watch task. You can alternatively do this from the command line:
cd source\Web
gulp watch
The TypeScript ng errors can be ignored
Run build.cmd to do a full rebuild, including tests, before submitting a code-change PR.