remove gardenfence from default admin blocklist

[fauno]

@RangerMauve also gardenfence is not required by default on sutty-managed websites, could you remove it too? -- #54

since it's out of reach for websites and the cms already manages this blocklist and others.

[sutty-coop]

Idea: have this as default if the site doesn't have a blocklist? @fauno can elaborate on this

[fauno]

Idea: have this as default if the site doesn't have a blocklist? @fauno can elaborate on this

that's the idea. this way the inbox still has a default protection but as soon as you start doing your own moderation it lets you do what you want.