removed checks related to udid and avd and added a check for udid only for ios.
Merge pull request #1010 from snevesbarros/adb_fix_error

Changes to allow installApp, removeApp and isAppInstalled to be called without providing a device id
Update troubleshooting.md

https://github.com/appium/appium/issues/1011
update selendroid to track dev branch instead of master