puppetboard: Adding PuppetDB 3.x support

Some excerpts from CHANGELOG.rst include:

• Increasing the pypuppetdb requirements from 0.1.x to 0.2.x
• The Reports page now lists reports from the reports endpoint instead of a link to a PuppetDB issue with a feature request
• Adding a Catalogs page to view either individual node catalogs or compare them against other nodes
• New environment awareness adds a new query parameter to all applicable endpoints to filter results based on the current environment. If the default environment 'production' is not available, or any other unavailable environment, the user is redirected to the first known environment.
• Adding pagination functionality for reports (for now) based on the value of the REPORTS_COUNT configuration option (used for the limit and the offset calculation). Implementation also makes it possible for other UI enhancements.
• Removing the limit_reports function from puppetboard/utils.py since paging parameters are now accepted by the pypuppetdb endpoint functions.
• Bumping the version to 0.1.0