Fix usage example.
Do not hardcode server address for frontend POST request.

Fixes #15.
Add presenter for code.google.com/p/... Go packages.

First cut.
Uses sourcegraph's currently existing vcsstore API.
Returns up to 20 commit messages.
Fix minor compile error.
Merge pull request #19 from shurcooL/add-code.google.com-presenter

Add presenter for code.google.com/p/... Go packages.
Work on porting frontend JavaScript code to Go.
Fix script.go having non-main package.

That resulted in main() not being executed. See gopherjs/gopherjs#75
and go-on/gopherjslib#3 for relevant context.
Remove unnecessary //gopherjs:blocking comment.
Add js build tag.
Do not hardcode server address for frontend POST request.