Closes #1074 : UI - Post deadline submissions

addition of a warning in the results/edit page for a post deadline
submission.
Checking in the controller instead of the view

Changing class 'error' with 'warning'
Another bug I forgot
Changing location of the method past_due_date? in model Grouping
Added new contributor
Add unit tests

(problem with commit)
Add RubyMine folder to .gitignore

 - .idea
add teardown with destroy_repos to do not have the error of filenames
Changing from result to results because of the has_many
Merge pull request #1076 from GhiGt/issue-1074

Closes #1074 : UI - Post deadline submissions
Merge pull request #1091 from GhiGt/rubymine

Add RubyMine folder to .gitignore
Merge pull request #1090 from benjaminvialle/NewContributor

Added new contributor
Update README.rst and markus-contributors.txt with students from UCOSP Winter 2013
Merge pull request #1093 from danielstjules/ucosp-contributors

Update README.rst and markus-contributors.txt with students from UCOSP Winter 2013
Merge pull request #1092 from GhiGt/patch-result

Changing from result to results because of the has_many