add imgur option

[ergofriend]

To use imgur, I changed vue-upload-component/file-upload option. https://lian-yue.github.io/vue-upload-component/#/documents#options-props-headers

options: {
    uploadUrl: "https://api.imgur.com/3/image",
    uploadUrlHeader: {'Authorization': 'Client-ID db856b43cc7f441'},
    file_input_name: "image",
    imgur: true,
 }

[manuelgeek]

it seems this pull request is never going to be accepted. But I do like your code. Exactly what i needed