Azure Cloud Storage support

Implemented in #54, first reported in #3.

With this release, uploads directly to Azure Cloud Storage are possible as described in the Fine Uploader Azure feature page. All core options, callbacks, and API methods specific to Fine Uploader Azure and inherited from the traditional endpoint uploader are also available with React Fine Uploader's Azure wrapper.

Also updated the minimal version of Fine Uploader to 5.11.10. Previously it was 5.11.5. A number of bugfixes occurred in the underlying library since 5.11.5. See the release notes in the fine-uploader project for details.