Open file for read in binary mode on requests.post
Open file for read in binary mode on requests.post

This seems to be a problem for the requests module in Python 3.
See https://3.python-requests.org/user/advanced/#post-multiple-multipart-encoded-files

Changelog: None

Signed-off-by: Lluis Campos <9244cb41c39addfc5cf236920b776ea2820513d0@northern.tech>

pasinskim/integration,pasinskim/integration,pasinskim/integration