Modernize development / rubygem environment.
Sign urls with ip_range '0.0.0.0/0' if none given.

Without SourceIp in the policy cloudfront responds with Malformed Policy.
The ip-range 0.0.0.0/0 will match every possible IP thus bypassing any IP requirement.
Merge pull request #3 from dbackeus/master

Modernize development environment and fix custom policies with no ip_range argument