Upgrade project to Django and Wagtail v2

[mtn]

It turned out to be easier than expected! Thanks @Parbhat 🎈

python runtest.py passes with Django v2, python3, wagtail v2.

[mtn]

I believe the tox tests should be modified, because they don't test the correct environments anymore. Is this right?

[Parbhat]

@mtn Great work. Correct we need to remove the python 2 related Travis tests. We probably need only Django 1.11.x and 2.0 on Python 3.4, 3.5 and 3.6

[mtn]

@Parbhat Got it. Can I just modify the tox.ini? Haven't used tox before.

[Parbhat]

@mtn Sure. Feel free to change the tox.ini and .travis.yml.

[mtn]

Hm, I found this to be fairly confusing. Build 67 passes without any 3.6 tests, but I can't make sense of how the tox environments are being run against different python versions. For example, in build 67, python 3.5 is run with a tox environment using 3.4? It might be clearest to look at the most recent build failure where I tried to add 3.6 tests but ended up with a bunch of configurations I didn't expect.

[mtn]

It looks like a combination I didn't expect is still being run, even after fixing the comma. File here.

Thanks for all the help!

[Parbhat]

@mtn Great start. .travis.yml also need to be updated to remove Django10 and add Django 2.

[mtn]

Hm, alright. Not quite working still -- I'll revisit this at some point. Let me know if anything stands out.

[mtn]

@Parbhat Is there any chance you'd be able to take a look and let me know if you have any suggestions on how to modify the tox or travis config files? Thanks for all the help!

[Parbhat]

@mtn The errors on Travis are all InterpreterNotFound errors like

ERROR:   py35-django20: InterpreterNotFound: python3.5

From the docs here, we need to update env value in .travis.yml to

matrix:
  include:
  - env: TOXENV=py34-django20
     python: 3.4
...
...
  -env: TOXENV=py35-django11
  python: 3.5

Specify the python interpreter along with TOXENV. An example can be seen in Wagtail project.

Let's try to do these changes.

Also, it seems that we should not drop support for Wagtail 1.13.1 as we can handle it with try / except block to fall back on the old import paths. We can update feeds.py like

from wagtail import VERSION as WAGTAIL_VERSION

if WAGTAIL_VERSION >= (2, 0):
    from wagtail.core.models import Site
    from wagtail.core.rich_text import expand_db_html
else:
    from wagtail.wagtailcore.models import Site
    from wagtail.wagtailcore.rich_text import expand_db_html

We can skip the tests for Wagtail 1.13.1

Please post here how it goes. Thanks.

[mtn]

Hm, unsure why travis isn't triggering a build, but at least for the versions of python I have locally (3.6) the tests are passing. I haven't added the line to maintain version 1.13.1 support yet. Will poke around a bit more before wandering off 🎈

Edit: Ah good, I found an error in the travis interface for the last commit. Edit 2: Tests seem good to go, let me know if you think otherwise!