Added an option to suppress excessive logging from UIALogger.

I've made a similar change to the downstream project [1][2][3] to suppress excessive logging from UIALogger.  @jlipps suggested me to patch the change back to this project.  Please let me know if any further info is needed.  Thanks.


[1]
https://github.com/appium/appium/pull/1436

[2]
https://github.com/appium/appium/commit/6c622ed73357aa212495a6d547c4d7001a817846

[3]
https://github.com/appium/appium/commit/6a39302db7b91e4831e4774a2f9300be6ff4e6a1