The MIT license doesn't require that all files be prepended with this
licensing or copyright information. Realm confirmed that they're ok with this
change. This will enable some companies to contribute to SwiftLint and the
date & authorship information will remain accessible via git source control.
This has never worked for two reasons:
1. We've used dictionaries to represent cache descriptions, which
don't guarantee stable ordering of keys across invocations.
This is true both on Darwin and Linux, but in practice ordering
varies significantly more on Linux.
2. Storing a `TimeInterval` value in a `[String: Any]` dictionary
and retrieving it again will not be dynamically castable to
`Double` or `TimeInterval` but will be castable to `Int`.
`fatalError` prints the full path of the file, which leaks filesystem information from the machine that built the binary. Now that we release via CocoaPods, this is more critical.