add version ex command

[nightwing]

#180

[masad-frost]

would it make more sense to import { version } from '../package.json'? We've done that in another cm package and it works fine with the build pipeline, not sure if it breaks for cm5.

[nightwing]

I did not manage to get cm build to inline version imported from package.json, and i did not want to leave require('../package.json'); in dist code. Also it would require more work to be compatible with web-demo.html .