Maybe I should add a bit more info, I was tired when I posted so I probably left some things out.

I've attached a picture showing how I connected everything. The servo worked when I used a transmitter and a receiver, but when I used the Raspberry Pi it did not. I tried with another type of servo (a Futaba S3003) but it didn't work either. I've seen other people use piblaster to control servos but for some reason it doesn't work.

Here's some short javascript code showing how I used the GPIO pin:

var piblaster = require("pi-blaster.js");

piblaster.setPwm(17, <some value>);