Refactoring notification library to avoid callback hell.
Refactoring notification library to avoid callback hell.

TomzxForks/gh,henvic/gh,TomzxForks/gh,tomzx/gh,oouyang/gh,modulexcite/gh,dustinryerson/gh,tomzx/gh,modulexcite/gh,dustinryerson/gh,henvic/gh,oouyang/gh