Add Jenkinsfile

Add rudimentary jenkinsfile to run the linter and build the project when
we open a new CR.
Add multistage builds in jami-web Dockerfile

Change-Id: Ifa3bbe20f14f944ec30ca10aa1a42fca6b3c2940
diff --git a/docker-compose.yml b/docker-compose.yml
index 7aef7d9..affc5ee 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -3,7 +3,9 @@
 services:
   jami-web:
     image: jami-web
-    build: .
+    build:
+      context: .
+      target: development
     volumes:
       # Add bind mounts for hot-reload
       - ./client/src:/web-client/client/src