Produce non-zero exit status on failure using strict

This PR makes `rdlint` return a non-zero exit status when run in `--strict` mode with one or more resource descriptors that produce an error.  This is necessary so that rdlint can be used with Kender.

@miwest929 @sheavalentine-mdsol @brutski 
`exit false` results in a status of `1`.  I was just following http://www.ruby-doc.org/core-1.9.3/Kernel.html#method-i-exit which looks like it takes a boolean from the method signature but it does say it can handle integers as well.