investigate an option to make appium/recorder and uploader dynamic per session

[vdelendik]

to be able to reuse the same device across different tenants we have make recorder and uploader dynamic, providing constantly actual parameters for this session.

that's might be a huge improvements including better scalability as every new appium request will use absolutely new container. I.e. global idea remove RETAIN_AGENT feature at all for mcloud and make it similar to zebrunner selenium grid: https://zebrunner.com/selenium-grid

this particular request depends on:
zebrunner/appium#195
and
zebrunner/mcloud-device#137