save
save
resumable put ok
use streamutil replace CopyTo
add downloadToken
update doc totally
base64urlsave use utf8 replace ascii
add package rpc
add CHANGELOG.md
update doc for fileop
Merge pull request #8 from shijiayun/master

ResumablePut
CHANGELOG v2.4.0
Merge pull request #11 from xushiwei/feature/release-v2.4.0

CHANGELOG v2.4.0
Merge pull request #10 from qiniu/develop

Release v2.4.0