Add missing package

[srus]

Spotted this after a fresh install.

[lorenzogil]

pyramid-debugtoolbar requires Pygments and pyramid_mako (which will probably depends on mako). As Yith is using pyramid_chameleon I rather not have two templating engines in our requirements.

So either we remove pyramid_debugtoolbar from config-templates/development.ini or we create a separate development.txt for development dependencies and update the docs to mention that you can install those dependencies just for development.

[srus]

Either option sounds good. Although since it's the only one, you could simply suggest pyramid-debugtoolbar as a useful package for development.