add apis and complete docs
modify doc formats
modify doc formats
fix some mem leak
update README.md
update README.md
Merge pull request #1 from chzyer/feature/add_gist

Feature/add gist
format change
format change
fix tab format
fix tab format
fix_batch_bugs_and_add_batch_tests
fix Makefile
merged
Merge pull request #92 from xushiwei/feature/add_apis

Feature/add apis
Update CHANGELOG.md
Merge pull request #93 from qiniu/develop

Release v6.1.2