Update GLM hierarchical binomial model to best practices (#45)

* 🎉 Add return_inferencedata and coords param task to pymc3 examples

* 🎨 Add coords into model instantiation and replace for var_names

* 🎨 Update GLM Hierarchical binom model notebook

* 🎨 Change halfflat prior to HalfNormal and plot customization

* 🎨 Change n reference into pm.Data ref

* 🔥 Remove testval param in prior from HalfNormal section

* 🎨 Update HalfNormal sigma from default to 10 to make prior less restrictive

* 🔥 remove commented code for kde plot replacement

Author: CloudChaoszero