delegate should be weak.
renamed delegate method to match apple style
strings should have copy attribute.
Added check if delegate responds to selector to avoid throwing exceptions
Redundant init methods.
Merge branch 'master' of https://github.com/cybertk/CKCountdownButton

Conflicts:
	Pod/Classes/CKCountdownButton.m
Fixed tests
Merge pull request #3 from tomkowz/master

Improvements