Merge branch 'release/0.3.1' into develop
add `position` spec, close https://github.com/ecomfe/saber/issues/33
fix doc
added setData, getData, removeData.
Merge branch 'develop' of github.com:ecomfe/saber-dom into develop
added data demo && update getData.
added dataset spec.
updated data spec & added data doc.
dataset has a bug in android 4.1, use getAttribute instead.
release 0.4.0
Merge branch 'release/0.4.0'