Flask version needs to be below 0.12

The standard install from GitHub currently installs the latest version of Flask, currently 1.0.2

This results in the error message

> ImportError: No module named ext.login

as due to deprecation in how Flask deals with extensions, this is no longer functional. More info at:

http://flask.pocoo.org/docs/0.12/upgrading/#extension-imports

To solve this, you need Flask maximum version 0.12, achieved by:

```
pip uninstall flask
pip install flask==0.12
```