use "build.ngseed.dev" domain for build

http://ngseed.dev -> /source
http://build.ngseed.dev -> /build


 __TODO__ use html2js for templates (seems like we need to update [gulp-html2js](https://github.com/fraserxu/gulp-html2js/blob/master/lib/compile.js) in order to support `fileHeaderString` and `fileFooterString` options).