Prepare 0.4.0 release
Prepare 0.4.0 release

pinball83/recyclerview-stickyheaders,msdgwzhy6/recyclerview-stickyheaders,eowise/recyclerview-stickyheaders,bingshanguxue/recyclerview-stickyheaders,chengkaizone/recyclerview-stickyheaders,akrezic1/recyclerview-stickyheaders