Using Lerna in the build and npm scripts, removing the hardcode.

[soumyajitsamanta]

Hi, I was debugging and during that I see the build process is bit manual at the moment and since the project is already using Lerna, I was thinking that npm scripts:

core:(dev/build/bundle/test),
2d:(dev/build/bundle/test),
ui::(dev/build/bundle/test),
template:(dev/build/bundle/test),
examples:(dev/build/bundle/test),
player:(dev/build/bundle/test),
docs:(dev/build/bundle/test)

can all be simplified to be:

build: "lerna run build",
bundle: "lerna run bundle",
test: "lerna run test",

This makes is easier and all packages can be operated on easily.
What do the developers think?