does a better job of finding a compatible recording when os=ios7

when testing on iOS 5 + 6 and os=ios7, i was seeing:

Playback not found: touch_done_ios7_iphone.base64

updated the code to search for the next existing recording

NOT TESTED ON THE IPAD
Merge pull request #175 from jmoody/0.9.x-load-playback-not-loading-anything-for-ios7

fix for 'Playback not found: touch_done_ios7_iphone.base64' when testing on iOS 5 + 6 and 'OS=ios7'