Enable the usage of arrays of cookbook directories

I have a local directory of custom cookbooks and then use
Berkshelf to pull in other cookbooks into a vendor directory.
This change allows users to supply not only an array of cookbooks
but a mix including multiple cookbook directories as well.
Adding a test proving mixed arrays work as well
Switch to Vagrant 1.5 compatability
Merge pull request #34 from jesseadams/feature/allow-multiple-cookbook-paths

Enable the usage of arrays of cookbook directories
Update changelog with PR
Update contributors
Put all dev dependencies into Gemfile, dont hardcode my file location
Attempt to get travis and Vagrant to play nice together
Force the right version of bundler
Swap bundler in the correct order
Try to get travis to install bundler
Force bundler upon travis
Avoid pesky prompts
Update travis badge
Update README.md

Minor spelling fix for "Compatability" section header to "Compatibility"
Merge pull request #49 from VMTrooper/README-update

Update README.md