update _core_en.js for rails3

since rails3 is the default, check in the new version so that others
don't get prompted to

test plan:
n/a, see spec ... in the real world compile_assets will ensure it is
current. this file is in version control to ensure dev i18n.js doesn't
asplode if you aren't compiling assets

Change-Id: I182b0864fd8fe4c4176fd71f695e19f6f7b405a9
Reviewed-on: https://gerrit.instructure.com/37795
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Cody Cutrer <cody@instructure.com>
Product-Review: Jon Jensen <jon@instructure.com>
QA-Review: Jon Jensen <jon@instructure.com>