Bug 835309 - Fix JarFileReader.readlines() and make flake8 happier. r=gps
Bug 835309 - Look at .xpi file contents when unifying them for universal builds. r=gps
Bug 836218 - Always copy files instead of skipping when destination is newer when doing l10n-repacks. r=ted
Bug 835214 - Avoid re-stripping executables already stripped. r=ted

Also rework UnifiedExecutableFile so that it leaves stripping to ExecutableFile.