Fix exception when trying to check Internet access

• Added a try-catch block around the check and finally to set the access to false: #8

Real User Monitoring

This release adds full support for Real User Monitoring.

• Call EnableRealUserMonitoring to automatically monitor a couple of application lifecycle events.
• Use the RaygunClient.ListenToNavigation attached property on a root Frame element to automatically capture page navigations on that Frame.
• Use RaygunClient.SendSession... methods to manually send events.

Look through the readme for more details.

Initial release with Crash Reporting

First release of Raygun4UWP. This can attach to the unhandled exception handler to automatically report exceptions to Raygun.com, and includes methods to manually report exception information.