Fixing automatic udid detection

Fix #1399
Merge pull request #1493 from penguinho/fix_udidetect

Fixing automatic udid detection
Adding the ability to get node path out of .appiumconfig (for users who modify .appiumconfig)
Improved getting .appiumconfig path location & now use JSON to parse .appiumconfig data.
Code style tweak to .appiumconfig file load/parse.
add chinese docs, add ruby xunit testcase example code for android