Enable race detection at tests (#239)

Author: diegobernardes

.travis.yml

@@ -27,10 +27,10 @@ before_script:
   - LINT_PKGS=$(go list ./... | grep -Ev 'aws-lambda-go/lambda')
 
 script:
-  - diff -u <(echo -n) <(gofmt -d ./)                              # Fail if a .go file hasn't been formatted with gofmt
-  - goverage -v -covermode=atomic -coverprofile=coverage.txt $PKGS # Run all tests with coverage
-  - go vet -v ./...                                                # static analyisis
-  - golint $LINT_PKGS                                              # lint - ignore failures for now
+  - diff -u <(echo -n) <(gofmt -d ./)                                    # Fail if a .go file hasn't been formatted with gofmt
+  - goverage -v -race -covermode=atomic -coverprofile=coverage.txt $PKGS # Run all tests with coverage
+  - go vet -v ./...                                                      # static analyisis
+  - golint $LINT_PKGS                                                    # lint - ignore failures for now
 
 after_success:
   - bash <(curl -s https://codecov.io/bash)