Update VSCode config

.gitignore

@@ -10,4 +10,5 @@
 /errors_app.log
 .coverage
 /.ropeproject
-/venv
+/venv
+.elixir_ls

.vscode/extensions.json

@@ -0,0 +1,5 @@
+{
+    "recommendations": [
+        "elixir-lsp.elixir-ls"
+    ]
+}

.vscode/settings.json

@@ -4,5 +4,6 @@
     "python.linting.pylintEnabled": false,
     "python.linting.flake8Enabled": true,
     "python.linting.enabled": true,
-    "elixir.projectPath": "backend/"
+    "elixirLS.mixEnv": "dev",
+    "elixirLS.projectDir": "backend/"
 }