Support PKCE auth flow & cleanup code (indico#10)

* Refactor code and add PKCE flow option
* Add and apply indico linting rules
* Use same date format everywhere

.editorconfig

@@ -0,0 +1,9 @@
+root=true
+
+[*]
+indent_style=space
+indent_size=2
+end_of_line=lf
+charset=utf-8
+trim_trailing_whitespace=true
+insert_final_newline=true

.eslintrc.yml

@@ -0,0 +1,17 @@
+env:
+  browser: true
+  es6: true
+
+extends:
+  - 'indico'
+  - 'indico/prettier'
+
+rules:
+  no-implicit-globals: off
+  no-unused-vars: off
+  no-undef: off
+  strict: off
+  prefer-template: error
+
+parserOptions:
+  ecmaVersion: 2018

.prettierrc

@@ -0,0 +1 @@
+"eslint-config-indico/prettier-config"

THANKS.md

@@ -11,11 +11,4 @@ and easier web development.
 Code licensed under Apache License v2.0, documentation under CC BY 3.0.
 <http://getbootstrap.com/>
 
-ui-bootstrap are the native AngularJS (Angular) directives for Twitter's Bootstrap.
-<http://angular-ui.github.io/bootstrap/>
-
-jsOAuth is a Javascript implimentation of the OAuth protocol.
-<http://bytespider.github.io/jsOAuth/>
-Licensed under MIT license
-
 See also the AUTHORS.