Merge pull request #95 from longshanksmo/develop

adjust download domain
mv qiniu/api/seekable => qiniu/bytes/seekable
Update README.md
Update README.md
upgrade resumable up interface
modify docs
rm useless comment
rm useless comment
modify resumable/io unit testing
update
update
Merge pull request #97 from wangtuanjie/feature/new_mkfile_interface

Feature/new mkfile interface
Update CHANGELOG.md
put policy
Merge pull request #99 from xushiwei/feature/put-policy

put policy
fix docs
fix docs
fix unit testing
Merge pull request #100 from wangtuanjie/fix/docs

Fix/docs