Build binaries using Go 1.3

Currently binaries are built using Go 1.2.2, which results
in larger binaries than those produced by newer versions of
Go. The Go source archive used for the build process is not
verified against its SHA1 hash.

Update the build-image Dockerfile to use Go 1.3 to build all
binaries, as a result binaries are now 20% - 30% smaller. The
Go source archive used for building binaries is now verified
against its SHA1 hash.
Merge pull request #633 from kelseyhightower/go1.3-build

Build binaries using Go 1.3
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