Style fixes (via vint) (#662)

This also adds a augroup for `jedi#add_goto_window`.

.travis.yml

@@ -1,7 +1,25 @@
 sudo: false
 language: python
+env:
+  matrix:
+    - ENV=test
+    - ENV=check
+matrix:
+  allow_failures:
+    # Needs to be fixed!
+    - env: ENV=test
 install:
-    - pip install pytest
+  - |
+    if [ "$ENV" = "check" ]; then
+      pip install vim-vint
+    else
+      pip install pytest
+    fi
 script:
-    - vim --version
-    - py.test
+  - vim --version
+  - |
+    if [ "$ENV" = "check" ]; then
+      vint after autoload ftplugin plugin
+    else
+      pytest
+    fi