update gem dependencies
Merge branch 'master' of github.com:easemob/developer.easemob.com
Merge branch 'master' of github.com:easemob/developer.easemob.com
Merge branch 'master' of github.com:easemob/developer.easemob.com
Merge branch 'master' of github.com:easemob/developer.easemob.com
Merge branch 'master' of github.com:easemob/developer.easemob.com
Merge branch 'master' of github.com:easemob/developer.easemob.com
remove nav header