Unit 3 / lesson 5 ported to F#

[Youenn-Bouglouan]

And this is the last one :)!

Uses version 1.2.0 of Akka.FSharp.
I had to change pattern matching a bit in the githubCommanderActor so it can match against ReceiveTimeout messages too:

let! message = mailbox.Receive ()
match box message with
| :? ReceiveTimeout as timeout -> // handle ReceiveTimeout messages
| :? GithubActorMessage as githubMessage -> // handle other messages as before
// rest of the code...

The rest is unchanged.

[Youenn-Bouglouan]

@Aaronontheweb once Lesson 3 / 4 / 5 get merged I'll have 2 more smaller PRs coming:

1. Move / rename a few folders in Unit 1 and Unit 3 so it follows the same structure as the C# bootcamp
2. Fix all the dead links to the docs

And that should be all for the F# bootcamp.

[Aaronontheweb]

Sounds good @Youenn-Bouglouan ! Excellent work. We should also link to the FSharp version from the readme file too. You've done an amazing job.

[Youenn-Bouglouan]

Thanks @Aaronontheweb it was fun to do! I just submitted #247 that fixes the remaining stuff.

Almost forgot about the link to the F# version, thanks for pointing that out. Will submit a new PR to the C# branch in a moment.