Membership settings

Added a contribution to the settings page and use these settings to manage memberships

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@huboard:{"order":8.5,"milestone_order":16,"custom_state":""}
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it is now parsed once submit is pressed, I could add a debouncer, but I really don't think it is necessary. The problem is if I parse it now is that `3.` would instantly become `3` making the only way to have floats to have `31415` and add a `.` to get `3.1415`