If you max your charisma and get the Bobblehead you can get to 21?

Are there any mods yet that allow you to bump up the settler limit?

http://www.nexusmods.com/fallout4/mods/828/?

I'm personally staying away from mods until more patches come out and until the Creation Kit has been released.

Nevermind.

This one is easier to use and doesn′t fiddle with your charisma.

http://www.nexusmods.com/fallout4/mods/1613/?

Oooooooooo ty