Fixed boot order for themes services
Fixed boot order for themes services

refs https://github.com/TryGhost/Ghost/commit/c33b596e9c9d912ed279140c1b0b60738dcd440a

- initializing the themes service before the custom theme settings service meant that `customThemeSettings.api` was not available when it's called as part of theme initialization
- swapped the boot order around so that the supporting service initialization is performed before the full themes service is initialized

ErisDS/Ghost,ErisDS/Ghost,TryGhost/Ghost,e10/Ghost,janvt/Ghost,TryGhost/Ghost,TryGhost/Ghost,e10/Ghost,janvt/Ghost,ErisDS/Ghost