circle 2.0 across all repos

[chriddyp]

We still have a few repos that we need to migrate to circleci 2.0.

These repos need to be migrated:

• dash
• dash-core-components
• dash-html-components
• dash-renderer
• dash-docs

But for consistency, here are all of the dash repos we're testing:

• dash
• dash-core-components
• dash-html-components
• dash-auth
• dash-renderer
• dash-table (private right now)

While we're at it, let's:

• Add the 3.7 container to all of our repos
• Remove tox
• Make sure that pylint and flake8 are set up
• Add eslint and prettier tests

We've done the migration in a couple of places:

• dash-auth: https://github.com/plotly/dash-auth/blob/master/.circleci/config.yml (still uses tox though)
• I tried to make this a little drier in the spring with this PR: https://github.com/plotly/dash/pull/222/files. It might be a good starting point. I don't remember the status of it.

[chriddyp]

@T4rk1n - could you take this one? I'm happy to give you a hand if you need it. The more people that are familar with circle the better :)

[chriddyp]

We have 3 weeks until they sunset 1.0

[T4rk1n]

I'll start with dash.

[T4rk1n]

I got the dash repo to work with 2.0 and tox. I added python3.7 tests, it was failing at pylint because it's not fully supported for python 3.7 yet, there is a pre release that works but they added some rules that fails.

[T4rk1n]

I think after plotly/dash-docs#178 all is done. Only some pylint/flake8 is missing from dcc and dash-docs, but they need alot of work to not fail.