Issues raised after enabling golint as part of golangci-lint
* error var ToDiscoveryError should have name of the
form ErrFoo (golint)
* error strings should not be capitalized or end with punctuation
or a newline (golint)
Issues not raised by golint embedded within golangci-lint
* comment on exported function <funcname> should be
of the form "<funcname> ..."
So kept the golint standalone tool also in Makefile
Change-Id: I7f2ce66d1e757bc24c042fc212226cecea297f27
fffc42ad8a