Drop go 1.4 and update tools/docs appropriately

.travis.yml

@@ -1,8 +1,7 @@
 language: go
 go:
-- 1.4.3
-- 1.5.3
-- 1.6
+- 1.5.4
+- 1.6.1
 
 env:
   global:

Makefile

@@ -7,18 +7,15 @@ vet:
 	go vet ./...
 
 errcheck:
-	@if go version | grep -q go1.5; then errcheck github.com/Shopify/sarama/...; fi
+	errcheck github.com/Shopify/sarama/...
 
 fmt:
 	@if [ -n "$$(go fmt ./...)" ]; then echo 'Please run go fmt on your code.' && exit 1; fi
 
-install_dependencies: install_errcheck install_go_vet get
+install_dependencies: install_errcheck get
 
 install_errcheck:
-	@if go version | grep -q go1.5; then go get github.com/kisielk/errcheck; fi
-
-install_go_vet:
-	go get golang.org/x/tools/cmd/vet
+	go get github.com/kisielk/errcheck
 
 get:
 	go get -t

README.md

@@ -18,7 +18,7 @@ Sarama is an MIT-licensed Go client library for [Apache Kafka](https://kafka.apa
 Sarama provides a "2 releases + 2 months" compatibility guarantee: we support
 the two latest stable releases of Kafka and Go, and we provide a two month
 grace period for older releases. This means we currently officially support
-Go 1.6, 1.5 and 1.4, and Kafka 0.9.0 and 0.8.2, although older releases are still
+Go 1.6 and 1.5, and Kafka 0.9.0 and 0.8.2, although older releases are still
 likely to work.
 
 Sarama follows semantic versioning and provides API stability via the gopkg.in service.