E401 project (sum12-csc517) to merge E303 feature to expertiza-master

* This is part of E401 project (sum12-csc517) to merge E303 feature to
expertiza-master.
* This is the first commit.
* This was tested with admin, instructor and normal users (all worked
fine).
* Two files may have to be reverted.  Read below for details of those
files.
* The tests (from e303 & new) are not checked in this commit.

File: app\controllers\assessment360_controller.rb
-------------------------------------------------
1. removed line:161. This was unnecessary code in the first loop
meta_scores = assignment_participant.get_metareviews()

2. edited line:167, as per E303 changes.

File: app\models\response.rb
----------------------------
1. Added below methods from E303
* get_alternative_total_score()
* get_maximum_score()
* get_average_score()

File: app\views\assessment360\all_student_all_reviews.html.erb
--------------------------------------------------------------
1. This file has all the changes to display the aggrgated meta review
and team-mate review scores for all students within a course.

2. Also added "Back to courses" and "Back" links at the botom of page

File: app\views\assessment360\one_course_all_assignments.html.erb
-----------------------------------------------------------------
1. Added "Back" link at the bottom of page

File: app\views\tree_display\actions\_course_actions.html.erb
--------------------------------------------------------------
1. Added the new icon and link on the right menu while hovering each
course.
The new link/icon is to launch/view the aggregated meta/team-mate review
scrores.

File: public\images\tree_view\view-team-meta-reviews-24.PNG
-----------------------------------------------------------
1. The new icon file added for "aggrgated meta review and team-mate
review summary"

File: app\models\response_map.rb
--------------------------------
1. Due to performance issue, I've copied the changes in E303 for method:
self.get_assessments_for(participant)
i.e the existing method in expertiza-master is commented,
Instead copied the method "self.get_assessments_for(participant)" from
E303.
I'll revert back this change if Expertiza teams do not confirm to hold
it.

File: db\schema.rb
-------------------
1. This file was autogenerated after
a. loading the new mysql db from expertiza-scrubbed.sql file.
b. rake db:migrate
I'm not sure if this need to be checked in.
Anyways checking in this for the time being but will revert back unless
Expertiza teams do not confirm to hold it.