Remove vendor/ (#688)

Vendoring seems to be problematic with go modules.
In addition to causing issues with transitive dependencies and being
problematic when trying to pull in the node-cli code, it also seems to
be pulling different versions than what is computed in go.mod.
This can be seen by comparing commits from the computed version in
go.mod with very small diffs (like a single Godep change in k8s) but massive
vendoring changes.

Basically I have very little confidence that this is even working.
This should be better in go1.13, but this is not released yet.

Makefile

@@ -38,7 +38,7 @@ build: build_tags := netgo osusergo
 build: OUTPUT_DIR ?= bin
 build: authors
 	@echo "Building..."
-	$Q CGO_ENABLED=0 go build -mod=vendor -ldflags '-extldflags "-static"' -o $(OUTPUT_DIR)/$(binary) $(if $V,-v) $(VERSION_FLAGS) ./cmd/$(binary)
+	$Q CGO_ENABLED=0 go build -ldflags '-extldflags "-static"' -o $(OUTPUT_DIR)/$(binary) $(if $V,-v) $(VERSION_FLAGS) ./cmd/$(binary)
 
 .PHONY: tags
 tags:
@@ -51,13 +51,7 @@ release: build goreleaser
 
 ##### =====> Utility targets <===== #####
 
-.PHONY: clean test list cover format docker vendor
-
-vendor:
-	@echo "Ensuring Dependencies..."
-	$Q go env
-	$Q go mod vendor
-
+.PHONY: clean test list cover format docker
 mod:
 	@echo "Prune Dependencies..."
 	$Q go mod tidy
@@ -85,11 +79,11 @@ endif
 test:
 ifndef CI
 	@echo "Testing..."
-	$Q go test -mod=vendor $(if $V,-v) $(allpackages)
+	$Q go test  $(if $V,-v) $(allpackages)
 else
 	@echo "Testing in CI..."
 	$Q mkdir -p test
-	$Q ( GODEBUG=cgocheck=2 go test -mod=vendor -v $(allpackages); echo $$? ) | \
+	$Q ( GODEBUG=cgocheck=2 go test -v $(allpackages); echo $$? ) | \
        tee test/output.txt | sed '$$ d'; exit $$(tail -1 test/output.txt)
 endif
 
@@ -103,7 +97,7 @@ cover: gocovmerge
 	$Q rm -f .GOPATH/cover/*.out cover/all.merged
 	$(if $V,@echo "-- go test -coverpkg=./... -coverprofile=cover/... ./...")
 	@for MOD in $(allpackages); do \
-        go test -mod=vendor -coverpkg=`echo $(allpackages)|tr " " ","` \
+        go test -coverpkg=`echo $(allpackages)|tr " " ","` \
             -coverprofile=cover/unit-`echo $$MOD|tr "/" "_"`.out \
             $$MOD 2>&1 | grep -v "no packages being tested depend on"; \
     done