Speed up sencha compilation and move rimraf to devDependencies.

The upstream build script was running a full npm install instead of
taking advantage of electron-builder. This should prevent unnecessary
package recalculation for both regular node packages and recompilation
of native dependencies.

rimraf was in normal dependencies, but without squirrel can live in
devDependencies instead.

This should decently speed up all forms of package building.

package.json

@@ -5,8 +5,9 @@
 		"start:debug": "electron electron/main.js --enable-logging",
 		"test": "./node_modules/.bin/mocha test/tests/**/*.spec.js",
 		"sencha:clean": "rimraf ./build/production",
-		"sencha:compile": "sencha app build && cpy app/package.json build/production/Rambox/ && npm --prefix ./build/production/Rambox/ install ./build/production/Rambox/",
+		"sencha:compile": "sencha app build && cpy app/package.json build/production/Rambox/",
 		"sencha:recompile": "npm run sencha:clean && npm run sencha:compile",
+		"postinstall": "electron-builder install-app-deps",
 		"clean": "rimraf ./dist",
 		"clean:win": "rimraf ./dist/win-{ia32-,}unpacked",
 		"clean:linux": "rimraf ./dist/linux-{ia32-,}unpacked",
@@ -108,6 +109,7 @@
 		"csvjson": "5.1.0",
 		"electron-builder": "^20.26.1",
 		"mocha": "^5.2.0",
+		"rimraf": "2.6.2",
 		"spectron": "^3.8.0"
 	},
 	"dependencies": {
@@ -115,11 +117,10 @@
 		"auth0-lock": "^10.24.3",
 		"auto-launch-patched": "5.0.2",
 		"electron": "^2.0.6",
-		"electron-store": "2.0.0",
 		"electron-context-menu": "0.10.0",
 		"electron-is-dev": "^0.3.0",
+		"electron-store": "2.0.0",
 		"mime": "^2.3.1",
-		"rimraf": "2.6.2",
 		"tmp": "0.0.33"
 	}
 }