Remove dependency future

[benjaoming]

The use of future is causing problems because we are bundling dependencies statically for a distribution that targets py2+py3.

It was introduced because of #4 in PR #5

Hard to believe that someone would bundle dependencies, but in our case it's very relevant because we distribute python packages for net-less installation with everything bundled in. We can't use django-q for our packages because future is raising exceptions when loaded on Python 3:

learningequality/kolibri#1797

Anyways, it wasn't used in more than 1 single instance of from builtins import range.

Here are some other advantages:

• future redefines and monkey patches sys.modules for all other packages, perhaps not nice!
• It has 106 unsolved issues
• Removes a dependency, so makes everything nicer :)
• future was missing in README.rst description

I've fixed some more cases where range wasn't loaded in a backwards compatible way. You can say that even though future was added as a dependency, it wasn't used in a couple of cases where it should have (test code).

Reference

There was only one case of accessing something redefined by futures library.

ack-grep --python 'import.*queue'
ack-grep --python 'reprlib'
ack-grep --python 'socketserver'
ack-grep --python 'winreg'
ack-grep --python 'test.support'
ack-grep --python 'import.*html'
ack-grep --python 'html.parser'
ack-grep --python 'html.entites'
ack-grep --python 'import.*http'
ack-grep --python 'http.client'
ack-grep --python 'http.server'
ack-grep --python 'http.cookies'
ack-grep --python 'http.cookiejar'
ack-grep --python 'urllib.parse'
ack-grep --python 'urllib.request'
ack-grep --python 'urllib.response'
ack-grep --python 'urllib.error'
ack-grep --python 'urllib.robotparser'
ack-grep --python 'xmlrpc.client'
ack-grep --python 'xmlrpc.server'
ack-grep --python '_thread'
ack-grep --python '_dummy_thread'
ack-grep --python '_markupbase'
ack-grep --python 'itertools.*filterfalse'
ack-grep --python 'itertools.*zip_longest'
ack-grep --python 'sys.*intern'
ack-grep --python 'collections.*UserDict'
ack-grep --python 'collections.*UserList'
ack-grep --python 'collections.*UserString'
ack-grep --python 'collections.*OrderedDict'
ack-grep --python 'collections.*Counter'
ack-grep --python 'subprocess.*'
ack-grep --python 'subprocess.*getoutput'
ack-grep --python 'subprocess.*getstatusoutput'
ack-grep --python 'subprocess.*check_output'

cluster.py
7:from builtins import range 

[codecov-io]

Codecov Report

Merging #247 into master will decrease coverage by 2.47%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #247      +/-   ##
==========================================
- Coverage   93.19%   90.71%   -2.48%     
==========================================
  Files          40       41       +1     
  Lines        2717     2724       +7     
==========================================
- Hits         2532     2471      -61     
- Misses        185      253      +68

Impacted Files	Coverage Δ
django_q/tests/test_brokers.py	70.58% <100%> (-11.7%)	⬇️
django_q/compat.py	100% <100%> (ø)
django_q/tests/test_monitor.py	100% <100%> (ø)	⬆️
django_q/tests/test_cluster.py	100% <100%> (ø)	⬆️
django_q/tests/test_cached.py	100% <100%> (ø)	⬆️
django_q/cluster.py	91.34% <100%> (-0.05%)	⬇️
django_q/brokers/ironmq.py	0% <0%> (-94.74%)	⬇️
django_q/brokers/__init__.py	94.18% <0%> (-2.33%)	⬇️

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[Koed00]

Nice. The 2.7 compatibility was a bit of an afterthought and I haven't had time to improve it.
At this point I will probably remove 2.7 when Django 2.0 arrives. Thanks for the effort; I will merge it soon.

[benjaoming]

Django 2.0 will also remove Python 2.7 compatibility - 1.11 is the last to support it: https://docs.djangoproject.com/en/1.11/releases/1.11/#python-compatibility

We have a couple of more additions in our internal branch that I'll ask people to PR upstream - thanks for the great project @Koed00 :)