add GitVersion configuration file (#1555)
add GitVersion configuration file (#1555)

* add GitVersion configuration file

* use beta tag for master

octokit/octokit.net,M-Zuber/octokit.net,M-Zuber/octokit.net,editor-tools/octokit.net,shiftkey-tester/octokit.net,gdziadkiewicz/octokit.net,shiftkey/octokit.net,octokit/octokit.net,TattsGroup/octokit.net,alfhenrik/octokit.net,thedillonb/octokit.net,alfhenrik/octokit.net,TattsGroup/octokit.net,gdziadkiewicz/octokit.net,editor-tools/octokit.net,shiftkey/octokit.net,thedillonb/octokit.net,eriawan/octokit.net,adamralph/octokit.net,eriawan/octokit.net,shiftkey-tester/octokit.net