v0.6.0

Changelog

547fa24 update version to 0.6.0
235f2d9 several readme updates
4f25f84 Merge pull request #10 from steven-zou/support_cert_and_ca
ce782fc Refactor code per reviewer's comments remove unnecessary comments change 'insecureSkipVerify' from upper case to camel style
58b3d65 fix conflicts with upstream repo
479486a Support pushing to the helm repo server which enable the https with certificates add --ca-file option add --cert-file option add --key-file option add --insecure option add UT cases for the newly appended options