Use goimports instead of gofmt

Everything except imports should be the same like with a direct call of
gofmt.

Imports will now be grouped into system packages, vendor packages and
kubevirt packages when calling "make fmt".

.travis.yml

@@ -20,14 +20,18 @@ install:
  - git reset --hard # we are caching the vendor folder, make sure we see the new vendor.json file
  - go get github.com/mattn/goveralls
  - go get -u github.com/kardianos/govendor
+ - go get golang.org/x/tools/cmd/goimports
  - go get -u github.com/golang/mock/gomock
  - go get -u github.com/rmohr/mock/mockgen
  - go get -u github.com/rmohr/go-swagger-utils/swagger-doc
  - sudo apt-get install libvirt-dev make
  - make sync
 
 script:
+ - make fmt
+ - if git diff --name-only | grep '.*.go'; then echo "It seems like you did not run `make fmt`. Please run it and commit the changes"; false; fi
  - make generate
+ - make fmt
  - if git diff --name-only | grep 'generated.*.go'; then echo "Content of generated files changed. Please regenerate and commit them."; false; fi
  - if diff <(git grep -c '') <(git grep -cI '') | grep -v 'swagger-ui' | grep '^<'; then echo "Binary files are present in git repostory."; false; fi
  - make check

Makefile

@@ -12,7 +12,7 @@ vet:
 	./hack/build-go.sh vet ${WHAT}
 
 fmt:
-	./hack/build-go.sh fmt ${WHAT}
+	goimports -w -local kubevirt.io cmd/ pkg/ tests/
 
 test: build
 	./hack/build-go.sh test ${WHAT}

docs/getting-started.md

@@ -61,7 +61,9 @@ to install a few build requirements:
 
 
     cd $GOPATH
-    # First we setup govendor which is used to track dependencies
+    # Use goimports for package import ordering
+    go get golang.org/x/tools/cmd/goimports
+    # Setup govendor which is used to track dependencies
     go get -u github.com/kardianos/govendor
 ```