* puppetboard/app.py: Adding Radiator view Part 2 of https://github.com/voxpupuli/puppetboard/issues/70 This is a refactoring of the changes in https://github.com/voxpupuli/puppetboard/pull/100. Adds a simple Heads-Up Display of the last run statuses of managed nodes, either environment filtered or not. * puppetboard/app.py: Fixing environment filters and metric strings. * The names of the population metrics have changes in PuppetDB 4.0, the initial commit used the metric names from PuppetDB 2.x. * The main nodes query did not include a query string to filter on environments.