Merge pull request #44 from jcabi/master

merge to my rep
Merge pull request #45 from jcabi/master

merge from master to my branch
Issue #331 - remove puzzle
Issue #343 - Remove puzzle
Merge pull request #450 from lthuangiang/issue343

Issue #343 - Remove puzzle
Merge pull request #449 from lthuangiang/issue331

Issue #331 - Remove puzzle
Merge remote-tracking branch 'upstream/master'