Fix #566: Number>>asNumber missing.
Added unit tests for Number.
Merge branch 'master' of github.com:amber-smalltalk/amber into github566

Conflicts:
	js/Kernel-Tests.deploy.js
	js/Kernel-Tests.js
	st/Kernel-Tests.st
Merge pull request #602 from matthias-springer/github566

Fix #566: Number>>asNumber missing.