New problem for Beginning Algebra

This question is a variant of another graphical interpretation question
but with step sizes of 1/2 instead of 1.
Merge branch 'master' of https://github.com/openwebwork/webwork-open-problem-library
Updates to sage app questions

These problems have been more appropriately tagged :) and many now
utilize the new sage macro instead of hardwired scripts.
Fix Tag

Hard to find a place to tag this all the way down.
Merge pull request #17 from drjt/master

Add a new problem for the PREP Model Courses