fix bad examples in readme
Merge branch 'master' of github.com:sendgrid/sendgrid-csharp
set target framework to .NET 4.5
remove RestSharp dependency, add Web API dependency. unstable
refactored to use System.Net.HttpClient. builds.
add nuget info
remove restsharp link
clean up dependencies
working on uploads
cleanup example, fix attachments
bump version
add nuspec and nupkg
update readme and example program
make Deliver and CheckForErrors methods async
Revert "make Deliver and CheckForErrors methods async"

This reverts commit 7d436f6cb48b1fe8f12949fea77bb7ea87fe3cc3.
change dependency from System.Net.Http to Microsoft.Net.Htpp
Update README.md
reorganize nuget stuff
set things up for both .NET 4.0 and 4.5
update readme