Use POST instead of GET when creating or updating resources

[fthorns]

Right now, almost all forms issue GET requests. This leads to long URLs and may contain confidential data, i.e. when creating a new container. In generally, it might be considerable to use POST instead of GET for all requests, that create or change resources.

[matthewalanpenning]

Thanks I agree!. In my porting of the software to Python from PHP, all the form data will use POST rather than GET.