Send files with POST request

[turnerrainer]

AS A Service Manager
I WANT to send files with POST request
SO THAT I could use such functionality where needed

Acceptance Criteria

• Regular http.post request
• Use contentType: file as an appendix

[RayDNoper]

Another usecase has to be added where files and formdata is both sent. Development in progress

[RayDNoper]

Due to another request updated the DSL syntax a bit more, now:
file:<fieldname>:<filename>: <content>