Incorporate code review feedback.

#1040 Empty SingleResult action should return 404

[OData] Register atomsvc+xml formatter first to respond to service do…

…cument requests in XML if no Accept header is specified

Fix another build race.

Use one version of the EntityFramework package, not two.

Fix for adding custom httproute. Before this fix, if one add custom

HttpRoute through the config.Routes.Add method, their GetRouteData method
and GetVirtualPath are ignored. Now it will get invoked properly.

Resolving client disconnection issues for self host server

Fixed issue with timings and SpanContextChanged flag.

Added extra "catch" around call to OnDocumentParseComplete handler to avoid bringing down the process due to a unhandled exception on a background thread.

Fixed sluggish editor behavior by removing Conditional Attribute opti…

…mization from design-time mode

Added copyright statements to files lacking it.

Fixing stress bug: The caching of the model validation node is causin…

…g a race during initialization. The stress test got null ref within 1 min. The hotfix is to turn off caching.