0.5.0

This is breaking release with no new features, just repacked JS version of DataScript so it can be used via modern JS dependency managers:

• Javascript version is now packaged as a proper CommonJS/RequireJS module (include via script tag still supported) (issue #39)
• Published to npm: npmjs.org/package/datascript
• [ BREAKING ] Javascript namespace is renamed from datascript.js to datascript