🐛BUG: Featbit SDK will not retry connection to eval server

[wss-rbrennan]

Problem:

If you start an application using the featbit client and it can't connect to the featbit eval server it will not retry and the application will use the hardcoded default flag value until it is restarted and it can reach the eval server.

Steps to reproduce:

1. Disable your eval server
2. Run the Sample aspnet core application
3. Observe the default flag values are used
   4, Re-Enable the eval server
4. Observe the default flags are still used.

Expected Behaviour

1. Disable your eval server
2. Run the Sample aspnet core application
3. Observe and DEBUG "Connection Attempt" log message is recorded
4. Observe and ERROR "Could Not Connect" log message is recorded
5. Observe the default flag values are used
   6, Re-Enable the eval server
6. Observe and DEBUG "Connection Attempt" log message is recorded
7. Observe the flags values are those provided by the eval server

The SDK should retry it's connection when it is unable to connect and should log connection attempts at the debug level and connection failures at the error level. It would be ideal if the retires followed an exponential delay pattern similar to k8s or as described in Wait and Retry with Exponential Back-off Here