Added class RateOfChange and methods for getting ROC for one date and a
specific period.
Changed name from RateOfChange to ROCHandler since the actual rate of
change is only a date, a stock and a percent rate. This should be an own
class.
Added and implemented the RateOfChange class with compareTo on rate and
a Comperator to be used for dates.
Implemented ROCHandler with constructor that creates an array of all
roc-ratios for a single stock.
Merge branch 'analyzer' of https://github.com/oskar-montin/datx02-stock-analyzer.git into analyzer