Android: Make ToolsViewer customizable in what tools to display

[zmarkan]

Split out from discussion here: #123 (comment)

Tools viewer currently has hardcoded tools to include. That is OK if users want all tools included, but if they only want a subset they would need to integrate independent tools reimplement the tools viewer functionality themselves.

Instead, we should make the tools viewer accept a list of tool objects provided by each library (based on a common interface).
Default behaviour should stay the same - include all tools, and if someone wanted to distributed just a subset of the tools they could pass in a custom list.