rails 5: fix i18n locale skipping
rails 5: fix i18n locale skipping

refs CNVS-34862

railties_load_path is a Rails::Paths::Path, instead of a simple string;
convert it to a simple string before assigning to I18n.load_path, the
same way that Rails' I18nRailtie does

Change-Id: I63353e771e4a372f3a7a8ef7c7a29d877a4ab2b9
Reviewed-on: https://gerrit.instructure.com/102207
Tested-by: Jenkins
Reviewed-by: Simon Williams <088e16a1019277b15d58faf0541e11910eb756f6@instructure.com>
Product-Review: Cody Cutrer <c4fe2b1d90ef8f2548c8aeabfa633434316f0305@instructure.com>
QA-Review: Cody Cutrer <c4fe2b1d90ef8f2548c8aeabfa633434316f0305@instructure.com>

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