test: remove obsolete run_build.sh script
js: remove Additional-Examples*.js (no .st files present)
CHANGELOG: mention Announcements and server HTTP authentication
README: add instructions to build Amber with Grunt.js
boot.js: set correct Package names in smalltalk.warpClassName()
remove peg-0.7.0.min.js as it is installed via npm
Merge pull request #416 from herby/jsobjproxy-at-ifpresent

JSObjectProxy >> at:IfPresent:{,ifAbsent:}
Merge pull request #415 from mkroehnert/cleanup

Changelog update, Grunt.js instructions, cleanup