Cleanup Makefile and .travis.yml (#305)

This fix updates .travis.yml and Makefile for several places:
- Remove unneeded `docker pull gcr.io/google_containers/hyperkube-amd64:v1.2.4` (only v1.3.7 was used)
- Use docker to deploy etcd (insteadof downloading etcd binary).
- Merge `make testk8s` and `make testk8s-setup` (no need to have multiple targets for a couple of tests)
- Set version of etcd and kubernetes in .travis.yml (so that it is easy to update new version in the future)

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

.travis.yml

@@ -11,6 +11,9 @@ go:
 
 go_import_path: github.com/miekg/coredns
 
+env:
+  - ETCD_VERSION=2.3.1 K8S_VERSION=1.3.7
+
 # In the Travis VM-based build environment, IPv6 networking is not
 # enabled by default. The sysctl operations below enable IPv6.
 # IPv6 is needed by some of the CoreDNS test cases. The VM environment
@@ -26,22 +29,12 @@ before_install:
   - env
 
 before_script:
-  # Download etcd, unpack and launch
-  - curl -L  https://github.com/coreos/etcd/releases/download/v2.3.1/etcd-v2.3.1-linux-amd64.tar.gz -o etcd-v2.3.1-linux-amd64.tar.gz
-  - tar xzvf etcd-v2.3.1-linux-amd64.tar.gz
-  - ./etcd-v2.3.1-linux-amd64/etcd &
-  # If docker is available, pull the kubernetes hyperkube image down and launch kubernetes.
-  - if which docker &>/dev/null ; then docker pull gcr.io/google_containers/hyperkube-amd64:v1.2.4 ; docker ps -a ; fi
-  - if which docker &>/dev/null ; then ./contrib/kubernetes/testscripts/start_k8s_with_services.sh ; docker ps -a ; fi
-  # Get golang dependencies, and build coredns binary
-  - go get -v -d ./...
-  - go get github.com/coreos/go-etcd/etcd
-    #- go build -v -ldflags="-s -w"
+  - docker run -d --net=host --name=etcd quay.io/coreos/etcd:v$ETCD_VERSION
+  - ./contrib/kubernetes/testscripts/start_k8s_with_services.sh
 
 script:
-  - go test -tags etcd -race -bench=. ./...
-  # Run kubernetes integration tests only if kubectl is available. i.e. If kubernetes was launched
-  - ./contrib/kubernetes/testscripts/kubectl version && go test -v -tags k8s -race -bench=. -run 'TestK8sIntegration' ./test
+  - docker ps -a
+  - ./contrib/kubernetes/testscripts/kubectl version
   - make coverage
 
 after_success: