Removed resource from ValueFormatters.

This was done to keep the purpose of the formatters focused.
Resource Instance now have context

Added context to resource instances. This cleans up a lot of method
signatures and prevents the need to manage context in other classes.
Context and formatter changes
Added missing syntax highlighting
clarification: 'Ruby object' instead of 'Ruby model'
Makes setup_request method private.
Merge pull request #28 from cerebris/context_rework

Context rework