Improve dockerfile to be slimmable

Change-Id: I1c0f62eca046ebc38f648ac8d650e286e810149b
diff --git a/.gitignore b/.gitignore
index d0db035..5818b15 100644
--- a/.gitignore
+++ b/.gitignore
@@ -46,4 +46,5 @@
 !.dockerignore
 /npm-debug.log
 /package-lock.json
-/kalamar.code-workspace
\ No newline at end of file
+/kalamar.code-workspace
+slim.report.json
\ No newline at end of file