Generates changelog for a github repository based on the closed issues.
###usage:
chanGenerator <user> <repository> <options>
Example:
Generate changelog since tag v1.1.1
chanGenerator <user> <repository> --show-categorized --tag v1.1.1
Generate changelog between 2015-01-01 and 2015-02-10
chanGenerator <user> <repository> --time-range 2015-01-01 2015-02-10
Generate changelog since commit 75c9687
chanGenerator <user> <repository> --commit 75c9687