Fix XR/Junos Cfg Replace

Title!

Preserve connection

Basically just some minor clean up ++ option to not close underlying scrapli connection when closing the scrapli cfg conn (super useful w/ context managers!)

py.typed! dont package tests, still alpha testing!

^^ title! fixes packaging that I broke in 2021.07.30a3 :)

2021.07.30a3

GitHub release will be same as 2021.07.30a4, but pypi 2021.07.30a3 was yanked as packing was broken!

Testing

2021.07.30a2

fix some links