Merge pull request #5 from boneskull/master

nextAutoIncrement() and tests
Updated tests to be faster, more accurate, and easier to read.
Added mongoose as a dev dependency.
- Added comments to plugin to make it easy to follow.
- Updated README to reflect certain changes to the API.
- Modified plugin to check if counters collection already exists. If so, use it.
- Modified nextAutoIncrement to nextCount for readability and a more concise API.
2.0.0
Modified README to include build, dependency, and npm badges.
2.0.1
Added .travis.yml file for Travis-CI build options.
2.0.2
Created free mongodb instance on mongolab to use for unit tests.
2.0.3
Figured out that travis-ci provides mongodb support. Changed connection string.
2.0.4
Update README.md
Update README.md
Update README.md
Update README.md
Updated package.json with the list of all contributors so far.
Added a CONTRIBUTING.md file to the root of the project to help others figure out how to contribute.
Update CONTRIBUTING.md