Configure TravisCI to test with testcgo tag.

.travis.yml

@@ -3,7 +3,7 @@ go: 1.2
 install:
     - go get -v code.google.com/p/go.tools/cmd/cover
 script:
-    - go test -v ./spew -covermode=count -coverprofile=profile.cov
+    - go test -v -tags=testcgo ./spew -covermode=count -coverprofile=profile.cov
 after_success:
     - go get -v github.com/mattn/goveralls
     - export PATH=$PATH:$HOME/gopath/bin