Migrate all dependencies to react@16

[oliviertassinari]

We are almost there. The only part missing is the test suite, 1200+ tests to migrate 😱.
It's going to be painful but let's do it! 💪

[leMaik]

@oliviertassinari What exactly needs to be migrated? Would you mind creating a TODO list to let us know where we can help you? 👍

[oliviertassinari]

I still have 110 tests that are red and need to pass. The biggest blocker seems to be related to Portal enzymejs/enzyme#1150. By migrated, I simply mean making the tests green.

[oliviertassinari]

I will push the branch as far as I can. But I will most likely not be able to complet it. This is my third iteration on the topic. If I fail, I will simply retro port the changes with react@15 so we move forward, one step at the time.

[leMaik]

@oliviertassinari Enzyme not supporting portals is a somewhat major blocking issue. I don't really get why nobody over there seems to bother about it. 😕

[oliviertassinari]

@leMaik I should manage to upgrade to enzyme@3. Only 4 more failing tests to fix. Then we are going to have to wait for portal support.

[oliviertassinari]

I'm gonna resume the effort. I'm gonna try to code branch the portal code for the tests. It might reduce the test coverage but it should allow us to close this issue.