Add basic CORS support

I don't really need it yet, but I had added it in as I was trying to
sort out how to get the UI working with the API

vanth/server.py

@@ -3,12 +3,17 @@ import uuid
 import flask
 import flask_login
 import flask_uuid
+import sepiida.cors
 import sepiida.endpoints
 
 import vanth.api.about
+import vanth.api.session
 import vanth.api.user
 import vanth.user
 
+EXPOSE_HEADERS = [
+    'Location',
+]
 
 def index():
     return flask.render_template('index.html')
@@ -45,6 +50,12 @@ def create_app(config):
         SECRET_KEY                = config.secret_key,
         SESSION_COOKIE_DOMAIN     = config.session_cookie_domain,
     )
+    sepiida.cors.register_cors_handlers(
+        app,
+        domains=['localhost:8080', 'www.vanth.com'],
+        supports_credentials=True,
+        expose_headers=EXPOSE_HEADERS,
+    )
 
     app.route('/', methods=['GET'])(index)
     app.route('/login/', methods=['GET', 'POST', 'DELETE'])(login)