Fix hack/build-go.sh to work on all platforms

Currently the hack/build-go.sh build script does not work
on OS X 10.9.x systems. This changes reverts back to building
one binary via a for loop.
Merge pull request #637 from kelseyhightower/fix-build-go

Fix hack/build-go.sh to work on all platforms
integration: Fix multiple response.WriteHeader calls

The current integration tests do not return after delegating
HTTP requests, as a result an extra call to response.WriteHeader
is made for every request.

Fix the issue by returning after delegating HTTP requests.
Merge pull request #638 from kelseyhightower/fix_multiple_response_write_headers

integration: Fix multiple response.WriteHeader calls
httplog: Improve test coverage
Merge pull request #644 from kelseyhightower/improve_httplog_test_coverage

httplog: Improve test coverage
Add a sanity check for running etcd servers to the integration test script.
Use http.StatusInternalServerError instead of 500
Fix typo in README
Merge pull request #652 from kelseyhightower/fix_readme_typo

Fix typo in README
Merge pull request #650 from smarterclayton/use_constant_code

Use http.StatusInternalServerError instead of 500
Merge pull request #645 from brendandburns/integration

Add a sanity check for existing etcd servers to the integration test script
Fixing typos
Merge pull request #658 from danmcp/fix_typos

Fixing typos
Fixing Typos
Merge pull request #660 from danmcp/fix_typos

Fixing Typos

Thanks for the fix.