A Polymer 1.0 element for image cropping and uploading.

The cropping is based on iCropper [https://github.com/supnate/icropper] by Supnate. It is modified to handle touch events.

Parameters:

• urlUpload
• authToken: optional authentication token (jws) for the header

<img-crop upload-url='[[uploadUrl]]' auth-token='[[authdata.token]]'></img-crop>