Bugfix-only release: Fix link delegation returning nil instead of false; documentation, warning and error handling improvements

• #122: Improve error message when server returns invalid data - @ivoanjo.
• #125: Add table of contents to readme and add note asking users to add their projects to the wiki - @ivoanjo.
• #127: Minor fixes: Fix warnings, and pry-byebug to dev Gemfile and tweak rubocop execution - @ivoanjo.
• #128: Fix link delegation returning nil for field with value false - @ivoanjo.

Bugfix-only release: Fix dropped values from queries by using FlatParamsEncoder

• #115: Fix dropped values from queries by using FlatParamsEncoder - @ivoanjo.