Add retains/releases, deallocs; update project.

• Added retains, releases, and autoreleases where appropriate.
• Added dealloc methods with release/nil-ing of properties and ivars to SVSegmentedControl and SVSegmentedThumb.
• Changed podspec to name “SVSegmentedControl.deARCed”, home/source to this repo (slippyd/SVSegmentedControl.deARCed), and requires_arc to false.
• In the project file, switched CLANG_ENABLE_OBJC_ARC to NO.
Update README with de-ARCed specifics.

• Appropriate names and URLs pointing to the de-ARCed version.
• ARC important note flipped to reference the original samvermette version.
• Sample code updated to match the demo it's pulled from (i.e. autorelease added).
• Added additional credit info about this fork and where to file issues.