v1.2.1 release

• feat - ttl method
• fix - inform subscribers when get the time expired
• doc - add english comments in source
• add ttl sample in readme

hotfix v1.1.3

global reference

v1.1.2 release

• improve types with global reference
• add logo
• add empty callback check

v1.1.1: Merge pull request #14 from dreambo8563/develop

add sessionStorage supported
separate alias $ls or $ss

v1.0: Merge pull request #10 from dreambo8563/develop

fix(typing): export vue wrapper