Fix mako incopatibilitie on pyramid chat example

[YuriAlessandro]

New Pyramid's version no longer support .mako (so as .chameleon) natively.

More informations: https://docs.pylonsproject.org/projects/pyramid/en/latest/whatsnew-1.5.html

Because of this, when you try to run the simple_pyramid_chat example you get an error. So, I updated the Pyramid example to support .mako (just putting him on the dependencies).

This error is mentioned in issue #189