add steps for building and testing to Readme.

[ofirgeller]

I tried npm install followed by grunt + <>//, got:
Fatal error: failed to lookup "tooltip"'s dependency "darsain-fuse"

[darsain]

I'd love to but right now the tooling is in a state of chaos and in-between things. Tooltip was built on top of component, but I want to migrate to duo, but that has still some issues. When that is done, I want to change the current old grunt setup to gulp.

As soon as this is sorted out I'll update the docs to reflect the changes.

I'm not even sure the current grunt tasks work. Maybe there has been some regression in dependencies. I'm currently using the raw component build --dev command for dev work.