Fix not shown 'exception page' on non windows system

Occurs on non windows system where Environment.NewLine is LF (1 symbol length) Unix, Linux, OS X etc. And options.ShowExceptionDetails is true.
Replaced number '2' to Environment.NewLine.Length.
Updating dev NuGet.config
Merge pull request #35 from turchenkoalex/bug-27

Issue #27: Error page middleware returns an empty body on OS X
Runtime information page
Fixup references
Fix ILibaryInformation.Version break.
Update helios dependency in samples.
replacing newlines inside the error message with the HTML br tag on error
page to properly dispaly the newlines on the error page
Reacting to CLR package versioning changes
New ErrorHandler middleware.
Fixed FakeLibraryInformation
Merge pull request #38 from tugberkugurlu/ErrorTitleShowNewLine

showing the error message inside pre tag in order to properly render the new lines
Cleaning up sample project.json

Primarily meant to remove reference to System.Security.Claims 1.0 package