Making innerPort dynamically assignable from predefined range and including innerPort auto-discovery will greatly simplify parallel execution of tests on different emulators.

Currently to run tests in parallel on same machine one would have to:

1. build n copies of .appx, but with different innerPorts,
2. start n copies of driver,
3. start n sessions against each driver with different innerPort capability.

All this hassle with innerPort is caused by the fact that emulators do forward their port to localhost. Maybe there is another way to deal with it, for example modifying Hyper-V machine settings or switch in someway, but it seems more invasive.

Adding port discovery will let us get rid of step 1 completely and simplify step 3.