Fix gatsby develop on npm3
Fix gatsby develop on npm3

Because npm3 dedupes packages by default, the ../../node_modules paths
assuming those packages are installed below gatsby in the tree fail
with:

    Cannot find module ... node_modules/gatsby/lib/utils/../../
    node_modules/webpack-dev-server/client?0.0.0.0:1826

Use `require.resolve` instead of relying the packages to be found in
a certain folder.

danielfarrell/gatsby,ChristopherBiscardi/gatsby,okcoker/gatsby,gatsbyjs/gatsby,chiedo/gatsby,Khaledgarbaya/gatsby,rothfels/gatsby,gatsbyjs/gatsby,mingaldrichgan/gatsby,0x80/gatsby,gatsbyjs/gatsby,Khaledgarbaya/gatsby,gesposito/gatsby,mingaldrichgan/gatsby,rothfels/gatsby,ChristopherBiscardi/gatsby,okcoker/gatsby,mickeyreiss/gatsby,chiedo/gatsby,okcoker/gatsby,ChristopherBiscardi/gatsby,chiedo/gatsby,danielfarrell/gatsby,danielfarrell/gatsby,gatsbyjs/gatsby,Khaledgarbaya/gatsby,gatsbyjs/gatsby,0x80/gatsby,fk/gatsby,fabrictech/gatsby,fk/gatsby,mickeyreiss/gatsby,fabrictech/gatsby,0x80/gatsby,ChristopherBiscardi/gatsby,gatsbyjs/gatsby,gesposito/gatsby,fk/gatsby,fabrictech/gatsby,mickeyreiss/gatsby,mingaldrichgan/gatsby