Add a verbosity concept to kubernetes scripts

The KUBE_VERBOSE environment variable sets the verbosity level to
use. Log messages can specify a verbosity by setting the V
variable. e.g.

    V=2 kube::log::info foo bar

Would only print "foo bar" if $KUBE_VERBOSE >= 2.

Makefile

@@ -49,6 +49,8 @@ META_DIR := .make
 KUBE_GOFLAGS := $(GOFLAGS)
 KUBE_GOLDFLAGS := $(GOLDFLAGS)
 
+KUBE_VERBOSE ?= 1
+
 GOGCFLAGS ?=
 BRANCH ?=
 KUBE_GOGCFLAGS = $(GOGCFLAGS)