Simplify babel integration further

The "react" preset is composed of a bunch of plugins.
https://babeljs.io/docs/plugins/preset-react/

Turns out, we only need 2 of them, not all 5.

bin/check-deps.js

@@ -45,7 +45,13 @@ var BUILT_IN_ELECTRON_MODULES = [ 'electron' ]
 
 var BUILT_IN_DEPS = [].concat(BUILT_IN_NODE_MODULES, BUILT_IN_ELECTRON_MODULES)
 
-var EXECUTABLE_DEPS = ['gh-release', 'standard', 'babel-cli', 'babel-preset-react']
+var EXECUTABLE_DEPS = [
+  'gh-release',
+  'standard',
+  'babel-cli',
+  'babel-plugin-syntax-jsx',
+  'babel-plugin-transform-react-jsx'
+]
 
 main()