add .gitignore
add objective-c README
[objective-c] add Bob exercise submission

First crack at writing some objective-c.  I actually wrote this on 4/22,
initially using an actual xcode project.  Environment was nicer but the
convenience of running the tests from the command line prompted me to
switch to the objc gem.

http://exercism.io/submissions/de63294c9586ae38624a20d5
[objective-c] add Hamming exercise submission

http://exercism.io/submissions/8632ec9b41c172bb36ef3c79
[objective-c] add WordCount exercise submission

http://exercism.io/submissions/69c7c92c5a3b44e575c9bf27