converted to ARC & removed target/action option to avoid the performSelector ARC ambiguity
added iOS test app and updated readme
removed some left-overs in the readme.
ARC makes code clean :)
renamed observee to observedObject
completed renaming observee to observedObject
added convenience method to create multiple observations with the same observed object, options and callback block for multiple key paths.
updated readme for multiple helper
added changelog
Merge branch 'release/v0.2'

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