Add Editor and more components

• CSS to be extracted
• [completed] Book-flight component
• Editor
  • save, cancel, and save & publish
  • edit title, excerpt, content (without image), featured image, category and tags
  • add post location (in progress)
• [completed] simple editor: self contained text-only medium editor component
• [completed] upload file: upload files of different kinds to server and return url, with preview using ng-file-upload
• [completed] rest api schema: no more hard coding of rest api endpoints as we now generate the functions at run time from the schema at the index. Cached too.