Jenkins setup. (#13)

* Adding test Jenkinsfile

* Will it be this simple?

* Maybe if I don't typo?

* Nuget restore needed.

* Work around NuGet bug hopefully.

The first person to run NuGet gets to own the /tmp/NuGetScratch folder, so jenkins breaks because I already ran NuGet personally.

* I'm a genius

Jenkinsfile

@@ -0,0 +1,18 @@
+pipeline {
+    agent any
+
+    stages {
+        stage('Setup') {
+            steps {
+                sh './RUN_THIS.py'
+                sh 'TMP=~/.cache/NuGet/ nuget restore'
+            }
+        }
+        stage('Build') {
+            steps {
+                sh './package_release_build.py --platform windows linux'
+                archiveArtifacts artifacts: 'release/*.zip'
+            }
+        }
+    }
+}