Provide a default InstUI modal for people to use
Provide a default InstUI modal for people to use

By using this instead of just importing directly,
You will get some sane defaults that make sense for canvas. So you don’t
Have to do set them every time

Test plan:
* See the Course image picker commit that uses this that is 
  based on this commit

Change-Id: I921d6a32fa62be8e061442669bb1e1ec0b6b2ebb
Reviewed-on: https://gerrit.instructure.com/136279
Tested-by: Jenkins
Reviewed-by: Clay Diffrient <9dff2e5c98626d20d2848250c411e8009465bb87@instructure.com>
Product-Review: Ryan Shaw <ea3cd978650417470535f3a4725b6b5042a6ab59@instructure.com>
QA-Review: Ryan Shaw <ea3cd978650417470535f3a4725b6b5042a6ab59@instructure.com>

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