More CLI options, less bloat and cleaner output

Highlights for this release

• Print dev-server URL in serve task
• The dev-server hostname is configurable
• Shrink the size of the package by 35mb
• Add support for CLI options verbose&profile
• Simplify the output of build and serve tasks
• SASS files in src/styles can be imported from anywhere without having to specify a path
• Allow build.conf.js to be absent in end projects
• Allow dependencies to be empty in end projects

Note: the gulpfile defining all Gulp tasks has been renamed from gulpfile.js to index.js (ac9bc1d). As a result, all end projects should update the path in their local gulpfile.js from node_modules/frontend-build/gulpfile.js to node_modules/frontend-build/index.js.