Fix dockerfile and improve linter and formatter

Fix wrong path in dockerfile.
Add `scss` file extension to "lint-staged" config so that prettier is
used to format `scss` files.
Set `eqeqeq` eslint rule severity to "error". Change all `==` instances in
old server code to `===`

Change-Id: Id0694f37556addc1c0cc05bc19e4e1fd1bd3411b
diff --git a/package.json b/package.json
index 2655563..c07f9ff 100644
--- a/package.json
+++ b/package.json
@@ -30,7 +30,7 @@
       "eslint --fix",
       "prettier --write"
     ],
-    "*.{json,md}": [
+    "*.{json,md,scss}": [
       "prettier --write"
     ]
   },