correct passing a 0 point value from assignment quick add "more options"
correct passing a 0 point value from assignment quick add "more options"

fixes CNVS-23940

test plan:
- create new assignment, provide a point value (remember point value)
- save new assignment, return to the assignment index page
- go to quick add ("+"), enter a title and date but leave value at 0
- click on "more options"
- initial point value on the edit page should be 0
- do not save new assignment, return to assignment index page
- click the main new assignment button ("+ Assignment")
- initial point value should match the point value entered in step 1

Change-Id: Ie0f0578e3c9b6274ead8d7614cc45c658627068a
Reviewed-on: https://gerrit.instructure.com/65357
Tested-by: Jenkins
Reviewed-by: Cameron Sutter <853bcc0cb8f5834b7805e8eb9a762054be43c731@instructure.com>
Reviewed-by: Ryan Taylor <2eafa1f6bf34395b543d6ca7f438461b0774d24f@instructure.com>
QA-Review: Michael Hargiss <59e3fde81b8d9a4f5e0cc016a3c2695591912604@instructure.com>
Product-Review: Jason Sparks <542e620f0c6c3447ce6e2e8c83a97102b99f89c6@instructure.com>

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