Upgrade to react 16

[Plsr]

Upgrades the project to react 16.2.0. On the way, some (minor) things needed to be adapted for the update to work.

• React was updated to 16.0.2
• tinycolor2 was added as a dependency. Before, it was imported from the node_modules of another dependency, which was, quite frankly, shit.
• devDependencies were added in the package.json file. Seems to be a leftover from the efforts to get a decent heroku build to work.
• engine and node version were adapted, so the travis jobs wont fail.