Add Travis, CodeClimate, and Jeweler

[francisluong]

• Add Travis CI for branch testing: https://travis-ci.org/ipaddress-gem/ipaddress/branches
• Add CodeClimate for test coverage and code review feedback: https://codeclimate.com/github/ipaddress-gem/ipaddress
• Use Jeweler to manage versioning and gemspec
• Updated Contributing.md to reflect use of Jeweler for versioning
• Cleaned up Readme.rdoc to remove version 1.0 mention and to add badges for build testing, coverage, etc

[francisluong]

# todo: clean up the readme and add testing/coverage badges

[francisluong]

@mikemackintosh: Think you can make some time in the next couple weeks to do a review on this PR?

[mikemackintosh]

I got it in my ToDo's for this week! Thanks