Support for Hangfire 1.0

Hello, @BredStik. I've included some changes to support Hangfire 1.0 version:

* Target projects to .NET Framework 4.5
* Update `Hangfire.Core` package to version `1.0.1`.
* Fix namespaces to `Hangfire.*` (lowercased `f` character).
* Replace `HangFire` with `Hangfire` everywhere.

Can you review these changes and push them to the NuGet Gallery?