Fixes Issue #331: Changes the Error Message When Programs are Missing (#497)

* changed error description for missing kubectl/kubelet execs

* adds function to generate error message for missing components

* adds function to generate error message for missing components

* adds function to generate error message for missing components

* Update cmd/util.go

Co-Authored-By: Liz Rice <liz@lizrice.com>

* Update cmd/util.go

Co-Authored-By: Liz Rice <liz@lizrice.com>

* Update cmd/util.go

Co-Authored-By: Liz Rice <liz@lizrice.com>

* Update cmd/util.go

Co-Authored-By: Liz Rice <liz@lizrice.com>

* Update cmd/util.go

Co-Authored-By: Liz Rice <liz@lizrice.com>

* fixed error message

* changes are per PR review