Use regex from machine_tag to validate tags, and add more tests
Updating version of strainer to 3.3.0
Moved require machine_tag to function that requires it.  Updated the comments on the tag tests.
Merge pull request #15 from rightscale-cookbooks/white_14_05_acu161542_perform_tag_validation_before_creating_tags

Use regex from machine_tag to validate tags, and add more tests
Bump version to 1.0.6
Update README based on format guidelines
Fix CentOS version in README