React v16

[mxstbr]

Currently, all last-draft-js-plugins depend on react@15.5. Now that react@16 has been out for a while it'd be great to add that version number to the peerDependencies!

[svnm]

Hi @mxstbr Thanks for your input. I have been a little inactive recently due to some other non programming commitments. If you have time to contribute, I could add you as a contributor to last draft and last draft plugins. I know you have a lot of other libraries you work on, it would be great to get your help, but only if you have the time. If not, I should hopefully be able to add this feature and a release of the other fix you worked on hopefully next week.

The main problem slowing down merging fixes was with draft-js-plugins I found it was quite complex getting the build for each of the modules, that is mainly due to the way styles are exported as css modules, and I didn't have a nice build step for this part. It is easier for changes like this one, which are just dependency or js changes. I wanted to use lerna for this project as well, which would make those fixes much quicker, but as mentioned don't have much time to implement it at the moment.

[mxstbr]

Yeah sure, it'd be great if you could add me to the repo!