1.6.2

• Fix MissingFormula namespacing. (@reitermarkus)
• Refactor and fix style for some specs. (@reitermarkus)
• x11_requirement: move download to base class. (@MikeMcQuaid)
• formula: sort aliases in to_hash. (@MikeMcQuaid)
• requirements: define cask on base class. (@MikeMcQuaid)
• formula: tweak to_hash bottle output. (@MikeMcQuaid)
• AbstractDownloadStrategy#safe_system : Don't splat 2nd arg to ErrorDuringExecution::new (@rayhamel)
• Xcode 9.3 (@ilovezfs)
• formula_support: deprecate more keg_only reasons. (@MikeMcQuaid)
• Remove Xcode.installed? guards. (@MikeMcQuaid)
• RuboCop 0.55.0. (@MikeMcQuaid)
• Cask Refactoring (@reitermarkus)