Fix bug in grading where some gateway problems use weighted grader.
Also, round off scores to 5 decimal places.
Caught one more instance where score could be rounded.
Merge branch 'develop' of github.com:openwebwork/webwork2 into develop
Merge pull request #466 from jwj61/develop

Fix gateway quiz bug and rounding

I checked this with a weighted answer problem.  The fix does correct the score reported at the top of the page.  I also checked the outputs and the score was formatted correctly.