Bug 812265, Part 1/4 - Remove JS_VERSION. r=dmandelin
Bug 812265, Part 2/4 - Setup versioning and pkg-config support. r=glandium
Bug 812265, Part 3/4 - Use version number in filename of shell and js-config. r=glandium
Bug 812265, Part 4/4 - Fix MOZ_JS_LIBS. r=glandium