Added "performance" log (wrightt).

Replaces https://github.com/ios-driver/ios-driver/pull/100.

Please review by Daniel Wagner-Hall (illicitonion).

Unrelated, server/pom.xml required a one-line change (line 47) to find libimobiledevice-java, but this might be specific to my mac/mvn setup:

    -        <groupId>libimobiledevice-java</groupId>
    +            <groupId>org.uiautomation</groupId>