Update ims-lti gem to support url encoded content in content items
Update ims-lti gem to support url encoded content in content items

fixes PLAT-2865

Test plan:
* Follow steps to reproduce
* Ensure that content item is successfully created

Change-Id: If8b3f3f2e662372b335463e0d4ca823a85ce9f69
Reviewed-on: https://gerrit.instructure.com/131916
Tested-by: Jenkins
Reviewed-by: Nathan Mills <10b0771d20c18ad0d98c1d000665e443052b40b0@instructure.com>
Reviewed-by: Stewie aka Nicholas Stewart <bec99285d8f1953757afca2af84365b0776c1eb4@instructure.com>
QA-Review: August Thornton <9adc7a1161ddf32ff608de792a7e50179545f026@instructure.com>
Product-Review: Andrew Butterfield <c9c7a32d9a1e9779cfad12bed963960e7af36eac@instructure.com>

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