Allows the context for the repl to be customized

If a context property is set on the config for the reptile plugin the properties will be added to the context of the repl
Tweak repl context test

Tests are failing on CI. Now using a different approach to test the same outcome
Merge pull request #9 from gingermusketeer/allow_customization_of_repl_context

Allows the context for the repl to be customized