Rename p_level to Goal Level
Added level descriptions. Students can now have a mastery level of 0.
Type of error descriptions.
Concept Progress edit form update
Dynamic next_steps selection to come
Next step selections dynamically chosen by Error Types.
Updated wording and images in About, Acknowledgements, and Sign Up pages.
Spec for Student editing Concept Progresses
Application helper spec
Concept Progress spec looks for correct default mastery level.
Fix concept show spec
Concept show spac
Revert "Concept show spac"

This reverts commit 04d3dd53f428cf645b182b14e7e9e04034cf3a01.
Concept show spec
Concept progress selection in spec
Yet another attempt with concept progress edit
Commented out concept progress edit lines until db is updated.
Merge pull request #121 from graspapp/changes

Project stage #2.