Added ConfidenceInterval class and BinomialConfidenceInterval providing implementations of several estimates of confidence intervals for binomial probabilities.
JIRA: MATH-1038
Patch provided by Thorsten Schaefer 


git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1533824 13f79535-47bb-0310-9956-ffa450edef68