Resolve WIndows command line quoting nightmare

In this release, I resolved issues from the previous release caused by the pathological handling of embedded quotes in Windows and PM2 command lines. The new APPIUM_DEFAULT_CAPS option wasn't being handled correctly on Windows, and the core of the fix was to leverage the fact that the Appium --default-capabilities option will accept a file path as its value. By using this facility, I was able to avoid all of the fruitless escaping of embedded quotes.