System.Reflection.Metadata.Tests: reference System.Threading contract assembly

This allows the test project to be built with Mono's xbuild.
Add FileVersionInfo tests
Fix typo: "informaiton" => "information"
Make _fileName readonly
Simplify ConvertTo8DigitHex
Fix spelling and whitespace
Cache the fallback lang-codepages
Cleanup ToString()

Use AppendLine and specify a larger capacity that is at least bigger
than the static strings.
Cleanup extraneous whitespace
Comment on the choice of the constant
Merge pull request #293 from mellinoe/add-fvi-tests

Add FileVersionInfo tests
Merge pull request #288 from akoeplinger/fix-sys.reflection.metadata-tests

System.Reflection.Metadata.Tests: reference System.Threading contract assembly
Merge pull request #301 from justinvp/fileversioninfo_cleanup

FileVersionInfo Cleanup