fill and and standardize docstrings

[jGaboardi]

Docstrings within region models are in several formats and there are quite a few missing argument explanations and example uses. See also @knaaptime's comments here, here, and here.

This is a running list of tasks. Update as needed.

• azp
• azp_util
• base (Region-k-means seed #294)
• components
• csgraph_utils
• maxp
• objective_function
• random_regions --> 857603a
• region_k_means
• skater --> (polish up docstrings, etc. in skater.py #335)
• spenc + spenclib/ (eec3ab2, ...)
• util --> d73e20d
• ward --> d6a1949