Add functionality to add an image to Issues and Issue comments

[nkoester]

This idea comes from the use cases where I often encounter

• issues (crashes etc.) on hosts which are not in the infrastructure, or
• errors which are displayed only shortly, or
• errors which are not logable otherwise

I'd love to take a picture of those and simply create/update an issue and append the image. To my mind, this saves a lot of time...

[indication]

Thank you for reporting the bug. There is a problem after create/update issue. (This may NullPointerException)