Django v2 compatibility testing

[grahamu]

• Add Django 2.0 compatibility testing
• Drop Django 1.9 and Python 3.3 support
• Add change log section to README
• Convert CI and coverage to CircleCi and CodeCov
• Add PyPi-compatible long description

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (master@04c74b9). Click here to learn what that means.
The diff coverage is 91.66%.

@@            Coverage Diff            @@
##             master      #28   +/-   ##
=========================================
  Coverage          ?   63.94%           
=========================================
  Files             ?       17           
  Lines             ?      294           
  Branches          ?       18           
=========================================
  Hits              ?      188           
  Misses            ?      103           
  Partials          ?        3

Flag	Coverage Δ
#py27dj110	43.87% <66.66%> (?)
#py27dj111	63.94% <91.66%> (?)
#py27dj18	43.87% <66.66%> (?)
#py34dj110	43.87% <66.66%> (?)
#py34dj111	63.94% <91.66%> (?)
#py34dj18	43.87% <66.66%> (?)
#py34dj20	63.94% <91.66%> (?)
#py35dj110	43.87% <66.66%> (?)
#py35dj111	63.94% <91.66%> (?)
#py35dj18	43.87% <66.66%> (?)
#py35dj20	63.94% <91.66%> (?)
#py36dj111	63.94% <91.66%> (?)
#py36dj20	63.94% <91.66%> (?)

Impacted Files	Coverage Δ
pinax/invitations/urls.py	100% <ø> (ø)
...invitations/templatetags/pinax_invitations_tags.py	0% <ø> (ø)
pinax/invitations/signals.py	100% <ø> (ø)
...nvitations/management/commands/infinite_invites.py	0% <0%> (ø)
pinax/invitations/models.py	75.9% <100%> (ø)
.../invitations/management/commands/topoff_invites.py	100% <100%> (ø)
pinax/invitations/views.py	61.03% <100%> (ø)
pinax/invitations/receivers.py	48% <100%> (ø)
...nax/invitations/management/commands/add_invites.py	100% <100%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 04c74b9...d624921. Read the comment docs.