amberc.js: async collecting and resolving of files
amberc.js: async collecting and resolving of files

resolve_js(): now takes a callback which gets called upon success
collect_files(): async search for .st and .js files
resolve_libraries(): split into 3 sub-functions
always_resolve(): takes a callback and calls it immediately
adrian-castravete/amber,matthias-springer/amber-athens,matthias-springer/amber-athens,adrian-castravete/amber,amber-smalltalk/amber,amber-smalltalk/amber,matthias-springer/amber-athens,adrian-castravete/amber,amber-smalltalk/amber