Update webview_test.rb

updating to latest selendroid-standalone.
Update user_registration_test.rb
fix for #74
increasing the stale connection timeout. Avoiding a potential ConcurrentModificationException

matching the standalone server to the same timeout... just in case.

Fixes Issue #76
Adding ability to specify -installedApp on command line.

Allows one to run tests locally without having the standalone server install an app every time.
some responses don't return a value all the time (like execute script without 'return')
changing the interface to pass the AndroidApp instead of a string to the apk file.

adding some printstacktraces to attempt to troubleshoot errors that happen on the server
(it's not nice to swallow errors anyways)
Logging output from any executed process
printing out exec sync output to help with debugging
adding retry logic for starting emulator
adding retries to starting instrumentation
adding logging for finding device
retry killing the emulator until it is really dead
handle killing emulator gracefully. kill adb server after 10 seconds of it starting up
actually pick the correct time to start trying to adb kill-server
Added logging to Selendroid Response to print the stack trace when exception occur
if instrumentation fails, retry the whole thing again (could be optimized to only re-install apps)
making installedApp really work now with an already started emulator