Filter out None points when calculating RTT

[RascalTwo]

Fix #14

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Filter's out the None points from latency_points to prevent the min, mean, and max from receiving any None values and throwing an error.

If preferred, I could use filter() over the list comprehension I used:

received_points = list(filter(bool, latency_points))

[dgzlopes]

Good catch @RascalTwo. Thanks a lot for the fix! LGTM.

I prefer the list comprehension, is more Pythonic 💯

On the other hand, can you add the changes for solving last latency_point not being included in RTT calculations issue?. If not, I can create one PR with the fix.

[RascalTwo]

Thanks, glad you like it - I also prefer the list comprehension too.

Would you prefer the last latency_point not being included in RTT calculations fix as a second commit to this PR or squashed into the one commit?

[dgzlopes]

Feel free to add a second commit. I can Squash and merge from the Github UI.

[RascalTwo]

All done - thanks for sharing this project and taking the time to review!

[jbarbaran]

Is this branch going to be merged with master?

[zatricky]

Would the None values indicate packet loss or timeouts? If so I'd consider that information useful. It's understandable if you're okay with simply discarding it - but it would be useful toward understand the situation with connectivity to an endpoint (which is the most likely reason someone is using tcp-latency in the first place).