Makefile: build kops in dev-mode by default
Makefile: build kops in dev-mode by default

The default makefile target should do a standard go install of kops
so we don't break existing workflows.

andrewsykim/kops,justinsb/kops,robinpercy/kops,chrislovecnm/kops,tsupertramp/kops,aledbf/kops,andrewsykim/kops,kubernetes/kops,robinpercy/kops,chrislovecnm/kops,gambol99/kops,kubernetes/kops,robinpercy/kops,blakebarnett/kops,aledbf/kops,mad01/kops,andrewsykim/kops,robinpercy/kops,pdh/kops,blakebarnett/kops,pdh/kops,chrislovecnm/kops,kubernetes/kops,tsupertramp/kops,tsupertramp/kops,gambol99/kops,gambol99/kops,tsupertramp/kops,mad01/kops,mad01/kops,blakebarnett/kops,aledbf/kops,pdh/kops,justinsb/kops,blakebarnett/kops,pdh/kops,justinsb/kops,aledbf/kops,chrislovecnm/kops,andrewsykim/kops,gambol99/kops,mad01/kops