Support SesionTTLMin configuration

[fraenkel]

• Allow setting SessionTTLMin
• Validate on the Server

[fraenkel]

Solves #796

[ryanuber]

This looks great! Thanks for tackling this. We just need another test for the config merging, and some supporting documentation, and with that I think we'll be ready to merge. Feel free to add that, or let me know and I'll be happy to wrap this up as well.

[fraenkel]

Updated with MergConfig support.

I will let you handle the supporting documentation. I wasn't sure if we wanted to go further and allow tweaking the Max and Multiplier but now at least we know all the spots if and when we do.

[ryanuber]

Thanks!