CYB-129 The 3 LTI Tools (PointsConfiguration, Gallery, and Leaderboard) should self-embed in Canvas

* adds thor tasks for each individually and one for all, to embed them in Canvas
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*   The ../config/.env_conf.yml file MUST have a new line added, so that Canvas can *
*    call back to the LTI tool to get the XML needed to make the configuration      *
*   the 'app' section for each Rails environment must have the 'lti_base_url' key   *
*   set to the location of the LTI app (DataCultures app), with trailing slash      *
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https://jira.ets.berkeley.edu/jira/browse/CYB-129