- fix update lable break connection with repository

- create new label

- fix isRead check
- fix paging

This change fixes the output from /{{ username }}.keys so that it can work in
a ~/.ssh/authorized_keys file

html, etc

According to http://golang.org/pkg/net/http/#DetectContentType
"If the Header does not contain a Content-Type line, Write adds
a Content-Type set to the result of passing the initial 512 bytes
of written data to DetectContentType."

This is because git command line shows the failure reason only if Content-Type is text/plain.

- fix delete user but repository watches are not decreased

README: fix typo