web: Improve upload workflow. - Add 'upload' and 'wikiupload' permissions, and check for them. - Fix the message about what the syntax is for using files in pages. - Fix uploading files to endpoint pages.

sudo: false
language: python
python:
  - "3.4"
  - "3.5"
  - "3.6"
install:
  - "pip install -r requirements.txt"
  - "pip install -r dev-requirements.txt"
script: py.test