Query Search Page (#1122)

* Query search page under SQL Lab tab

* Modifications based on comments

* Hash

* Added spec and endpoint test with modifications
based on second round comments

* Changed permission menu in https://github.com/airbnb/caravel/pull/1095/files

caravel/assets/javascripts/SqlLab/reducers.js

@@ -13,6 +13,7 @@ const defaultQueryEditor = {
   dbId: null,
 };
 
+// TODO(bkyryliuk): document the object schemas
 export const initialState = {
   alerts: [],
   networkOn: true,