feat: Add deprecation warnings for some props (react-dropzone#364)

In the next major release some props will be deprecated.
In order to smoothen the migration process deprecation warnings were added.

feat: Pass active/reject state to children during the drag operation (r…

…eact-dropzone#342)

Implement children as a function with `isDragActive` and `isDragReject` as arguments to allow rendering custom content depending on the dropzone's state.

fix(onClick): Propagate click events normally when `disableClick` is …

…`false` (react-dropzone#335)

If `disableClick` isn't set we don't want to call `stopPropagation` method on the event.

fix(preview): Remove filetype check for generating preview (react-dro…

…pzone#332)

Previews were disabled for everything but images. Some users report that you can actually generate previews for videos or PDFs so the check seems to be too strict in is now removed.

Fixes react-dropzone#318

feat: Allow passing a callback for onDragOver as a prop (react-dropzo…

…ne#326)

A callback for `onDragOver` event was missing in props. This PR adds it.

Closes react-dropzone#325

fix: Fix getting data transfer items from event object

Chore: Use node 6.x on Travis CI

fix(react-dom): filter out `acceptedFiles` prop to remove React warni…

…ng (react-dropzone#267)

* filter out `acceptedFiles` prop to remove warning
* reorder customProps list by alphabet

ci(CI): Dont't run tests twice on CI

build(npm): Switched to semantic-release and commitizen