Bug Fix: Issue #2

[DomHudson]

Summary

Adds django's MiddlewareMixin to ensure support for django >= 1.10 and also django < 1.10.

Closes

#2

[DomHudson]

I also altered

if sql[0][:6].upper() == 'SELECT':

to

if sql[0].upper().lstrip().startswith('SELECT'):

as it is more semantic, and covers the case where there are spaces at the beginning of the SQL like so:

sql = '''
SELECT id, name
FROM users
LIMIT 1;
'''