0.5

• don't re-execute modules once a dependant changes, just update the module bindings(!)
• instrument System.register setters to capture (and update) module bindings
• don't freeze modules by default to allow adding new exports without reloading dependent modules
• export fixes for async transformation. babel async transformer is
  surprisingly fragile as to where async functions are placed, in lively.ast and
  lively.modules we have some manual "hoisting" now to work around these issues
• support systemjs 0.19.30 + systemjs-babel-plugin for using babel@6
• fix wrapping nodejs modules as es6 modules
• replacing System["lively.modules"] with System.get("@lively-env")
• dont rewrite "fetch" as it is a function that apparently cannot be called as a method from a dereived global