fix(Injector): Injector component index was incorrectly placed.

Moved the component index into the execution of the HOC result of initial Injector function call.
This allows us to preconfigure the Injector HOC in the same location as the Injectable, and promotes
less code and more reuse.

src/Injector.js

@@ -21,16 +21,16 @@ const Injector = ({ into } = {}) => {
     // Error message
     invalidTargetMsg);
 
-  injectorIndex++;
-  const injectorId = `injector_${injectorIndex}`;
-
   return function WrapComponent(InjectionComponent) {
     invariant(
       InjectionComponent &&
       typeof InjectionComponent === `function`,
       invalidInjectMsg
     );
 
+    injectorIndex++;
+    const injectorId = `injector_${injectorIndex}`;
+
     class InjectorComponent extends Component {
       static contextTypes = {
         registerInjector: PropTypes.func.isRequired,