install bootstrap via composer

vendor/twbs/bootstrap/nuget/MyGet.ps1

@@ -0,0 +1,18 @@
+# set env vars usually set by MyGet (enable for local testing)
+#$env:SourcesPath = '..'
+#$env:NuGet = "./nuget.exe" #https://dist.nuget.org/win-x86-commandline/latest/nuget.exe
+
+$nuget = $env:NuGet
+
+# parse the version number out of package.json
+$bsversionParts = ((Get-Content $env:SourcesPath\package.json) -join "`n" | ConvertFrom-Json).version.split('-', 2) # split the version on the '-'
+$bsversion = $bsversionParts[0]
+
+if ($bsversionParts.Length -gt 1)
+{
+    $bsversion += '-' + $bsversionParts[1].replace('.', '').replace('-', '_')   # strip out invalid chars from the PreRelease part
+}
+
+# create packages
+& $nuget pack "$env:SourcesPath\nuget\bootstrap.nuspec" -Verbosity detailed -NonInteractive -NoPackageAnalysis -BasePath $env:SourcesPath -Version $bsversion
+& $nuget pack "$env:SourcesPath\nuget\bootstrap.sass.nuspec" -Verbosity detailed -NonInteractive -NoPackageAnalysis -BasePath $env:SourcesPath -Version $bsversion