Fixed potential divide by zero error

[DustinEwers]

This fixes issue: https://github.com/microsoft/fhir-loader/issues/23

If the FHIR request is completed in less than 1000 milliseconds, then the conversion would return zero seconds. This causes a divide-by-zero error. I modified the divisor to a double so it will perform a floating point calculation instead of an integer calculation.

[evachen96]

We refactored with telemetry client and the line in question no longer exists in main. Closing this out.