Update FSharp Formatting and fix documentation tests

This pull request

 * Updates to the latest F# Formatting
 * Simplifies the code in the doc test runner (this is a lot easier because F# Compiler Service *is* the F# compiler and so we do not need to search for `FSharp.Compiler.dll`)
 * Fixes a few things in documentation (add `[lang=text]` etc. because new F# Formatting colorizes nested code snippets, reflect MovieDb API change).