Fix some more XML docs
System.Reflection.Metadata.Tests: reference System.Threading contract assembly

This allows the test project to be built with Mono's xbuild.
Add Regex Tests
Add FileVersionInfo tests
Remove unused static _canUseAsync field

This was previously (Environment.OSVersion.Platform ==
PlatformID.Win32NT) but has since been updated to always be true.
This is now dead code that should be removed.
Fix typo: "informaiton" => "information"
Make _fileName readonly
Simplify ConvertTo8DigitHex
Merge pull request #289 from richamsft/master

Initial work to port System.Diagnostics.Process
Update README.md

Updated documentation for System.Diagnostics.Process
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
Canonicalize MSBuild ToolsVersion to 12.0

Right now, there's a mix of ToolsVersion 4.0 and 12.0 in the projects.
We should make sure that it's 12.0 everywhere.
Comment on the choice of the constant
Merge pull request #292 from mellinoe/add-regex-tests

Add Regex Tests
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