* Reduce code duplication and fix typo

* fix apihandler.go

* fix

* fix

* use golint

if block ends with a return statement, so drop this else and outdent its block

* use golint

apihandler.go:1168:2: var sessionId should be sessionID

* fix a space

* fix

* fix

* use golint in backend/cert and backend/client

* use golint

* fix

* fix