Updated Tesseract to 3.03 and Leptonica to 1.70

I've updated Tesseract to the 3.03 RC and Leptonica to 1.70 using this build script: https://gist.github.com/williamsodell/8846486

This update fixes the confidence value issue I reported in #56. Specifically, ```getConfidenceBySymbol``` no longer crashes for some images, and the Tesseract option "save_blob_choices" = T is no longer required to have the symbol confidences be reported correctly.

Note that building the Tesseract OCR Aggregate product will yield a warning about how the Tesseract and Leptonica lib files don't work for the x86_64 architecture. However, everything still works in the simulator, I guess because the libraries work okay with the i386 target.

Additionally, I modified the way the method ```characterBoxes``` works so that instead of returning a NSDictionary (which loses the order in which the recognized characters/boxes appear in the image), it instead returns an NSArray where each element is an NSDictionary with two key/value pairs: 1) "text" which is the recognized character and 2) "box" which is the bounding box for the character. Before I fixed the confidence value issue, I was using this modification to filter out "bad" characters by detecting irregular sized bounding boxes.