more go versions; add race detector to tests

.travis.yml

@@ -5,6 +5,10 @@ go:
     - 1.3
     - 1.4
     - 1.5
+    - 1.6
+    - 1.7
+    - 1.8
+    - 1.9
 
 script:
     - ./validate.sh

validate.sh

@@ -7,4 +7,4 @@ GOFMT_LINES=`gofmt -l . | wc -l | xargs`
 test $GOFMT_LINES -eq 0 || echo "gofmt needs to be run, ${GOFMT_LINES} files have issues"
 
 # run the tests for the root package
-go test .
+go test -race .