add some information about the Xposed binary and the phone into the log

For example:
D/Xposed  (19345): Starting Xposed binary version 30, compiled for SDK 17
D/Xposed  (19345): Phone GT-I9100 (samsung), Android version 4.2.1 (SDK 17)
D/Xposed  (19345): ROM: cm_i9100-userdebug 4.2.1 JOP40D eng..20130105.024510 test-keys
I/Xposed  (19345): -----------------
I/Xposed  (19345): Added Xposed (/data/xposed/XposedBridge.jar) to CLASSPATH.
I/Xposed  (19345): Found Xposed class 'de/robv/android/xposed/XposedBridge', now initializing