Make Android.prototype.getPageSource and
Android.prototype.getPageSourceXML also work under Windows:

Three Changes:
1) generate the temp file name using temp.path
2) split adb shell calls in 2 functions
3) remove temporary files
Quoted xmlFile in shell commands to prevent breaking the command if spaces were in the generated temporary file name
Merge pull request #830 from drpy/master

Make Android.prototype.getPageSource / getPageSourceXML also work under Windows