Fix POST reload on member

[c00k133]

When updating a member (or I guess anything) the JS used does a POST request to our backend. However, this POST request stays as the current history location, meaning that if you reload the page with, e.g., Ctlr+r on Firefox it fires the POST request again (with possibly altered data, depending on if the form has been altered).

This should be fixed as it is a pain to work with and might result in mangled data.