`filters.ToParam()` and `filters.FromParam()` were deprecated in favor of
`filters.ToJSON()` and `filters.FromJSON()` in 065118390a,
but still used in various locations.
This patch replaces uses of `filters.ToParam()` and `filters.FromParam()` with
`filters.ToJSON()` and `filters.FromJSON()`.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>