fix(omit): Strengthen the type checking of the omit utility function

Author: bfricka

modules/store/src/utils.ts

@@ -31,10 +31,10 @@ export function combineReducers(reducers: any, initialState: any = {}): ActionRe
   };
 }
 
-export function omit(object: { [key: string]: any }, keyToRemove: string) {
+export function omit<T extends { [key: string]: any }>(object: T, keyToRemove: keyof T): Partial<T> {
   return Object.keys(object)
     .filter(key => key !== keyToRemove)
-    .reduce((result, key) => (<any>result)[key] = object[key], {});
+    .reduce((result, key) => Object.assign(result, { [key]: object[key] }), {});
 }
 
 export function compose<A>(): (i: A) => A;