Bump version to 0.2.1.
Also run tests with 0.10 on travis-si.
Fix a bug with ignore params printing a file path even if there are no unused
variables.
Upgrade optimist dependency.
Update usage string, make sure ignore-params is a string.
Print a usage string if user uses --help option or doesn't pass any files to the
command.
Update usage string.
Add some tests for the cli and --ignore-params option.
Bump version.
Adding additional structure and CLI arg to allow the scanner to ignore all function parameters, since they're a common source of false positives
A couple minor changes based on pull request discussion