Added promotions to redux and added selector for setting promotions if not PRO

• Added:
- promotions to redux
- selector for setting promotions if not PRO

• Updated:
- StatusList, SidebarPanelGroup to use promotions from redux

app/javascript/gabsocial/reducers/promotions.js

@@ -0,0 +1,23 @@
+import {
+  List as ImmutableList,
+  fromJS,
+}from 'immutable'
+import {
+  PROMOTIONS_FETCH_REQUEST,
+  PROMOTIONS_FETCH_SUCCESS,
+  PROMOTIONS_FETCH_FAIL,
+} from '../actions/promotions'
+
+const initialState = ImmutableList()
+
+export default function promotions(state = initialState, action) {
+  switch (action.type) {
+  case PROMOTIONS_FETCH_REQUEST:
+  case PROMOTIONS_FETCH_FAIL:
+    return initialState
+  case PROMOTIONS_FETCH_SUCCESS:
+    return fromJS(action.items)
+  default:
+    return state
+  }
+}