Update NUI.podspec

NUI compiles properly and runs when the deployment target is set to 5.1. Any reason why the podspec is locked to 6.0?
Merge pull request #114 from markrickert/patch-1

Update NUI.podspec
Updated podspec to 0.2.9
Add tint color to UISearchBar
Add background-tint-color to SeachBar in README
Fix memory leak when drawing back button
Add iPad storyboard, Call renderSize before drawing layers for UIButton #126
Updated podspec to 0.3.0
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