Merge pull request #270 from rockfordlhotka/master

Merge HttpProxy/Host and Brokered Proxy/Host updates
Merge pull request #272 from rockfordlhotka/master

Version 4.5.581 prerelease
Merge pull request #273 from rockfordlhotka/master

#267 Add support for Windows Phone 8.1
Merge pull request #275 from rockfordlhotka/master

#274 Update version numbers.
Merge pull request #280 from rockfordlhotka/master

Improve exception handling and nuget package restore
Merge pull request #282 from rockfordlhotka/master

Version 4.5.582 prerelease
#283 Add WP8.1 assemblies to core definition.
Closes #283 version 4.5.583 prerelease
Merge pull request #31 from MarimerLLC/master

Update to latest