Migrate to dep (#3972)

* Update makefile to use dep

* Migrate to dep

* Fix some deps

* Try to find a better version for golang.org/x/net

* Try to find a better version for golang.org/x/oauth2

vendor/github.com/microcosm-cc/bluemonday/Makefile

@@ -1,42 +0,0 @@
-# Targets:
-#
-#   all:          Builds the code locally after testing
-#
-#   fmt:          Formats the source files
-#   build:        Builds the code locally
-#   vet:          Vets the code
-#   lint:         Runs lint over the code (you do not need to fix everything)
-#   test:         Runs the tests
-#   cover:        Gives you the URL to a nice test coverage report
-#
-#   install:      Builds, tests and installs the code locally
-
-.PHONY: all fmt build vet lint test cover install
-
-# The first target is always the default action if `make` is called without
-# args we build and install into $GOPATH so that it can just be run
-
-all: fmt vet test install
-
-fmt:
-	@gofmt -s -w ./$*
-
-build:
-	@go build
-
-vet:
-	@go vet *.go
-
-lint:
-	@golint *.go
-
-test:
-	@go test -v ./...
-
-cover: COVERAGE_FILE := coverage.out
-cover:
-	@go test -coverprofile=$(COVERAGE_FILE) && \
-	cover -html=$(COVERAGE_FILE) && rm $(COVERAGE_FILE)
-
-install:
-	@go install ./...