Add CHANGELOG

CHANGELOG

+Afterwards: I extended the library for dealing with bigger timespans and 
+negative date. 
+I therefore added my own object for handling dates and integrated it into the 
+code instead of using JavaScript Date, changed parsing of the input strings, 
+added more possible scales and the output for these different scales.
+
+initial commit: 
+cloned library from https://github.com/ka215/jquery.timeline (author ka215)
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