Adding Javascript runtime to MarkUs
Warn user if bundler version is to low

As we are enabling the support for ruby 2.0 platform (mri_20 in
Gemfile), we need to have Bundler >= 1.3.5
When there is no marks self.total_mark is 0. Condition is used to avoid division by 0.
Fix issue #1388
Merge branch 'master' of git://github.com/MarkUsProject/Markus
Merge branch 'master' of git://github.com/MarkUsProject/Markus
New test: if an assigment has no marks and was completed and released to student should has values median and average results values equal to 0. 

Equation that divides by total marks (0 if no marks in the assingment) should not be reached.
Correcting lines that are setup and verification.
Correcting comment.
Verify if students_counts is not zero, avoiding division by zero
Fix: schema.rb
Merge branch 'issue-1333'
Merge pull request #1336 from benjaminvialle/execjs

Adding Javascript runtime to MarkUs
Merge pull request #1386 from benjaminvialle/bundler

Warn user if bundler version is to low
Merge branch 'master' of github.com:MarkUsProject/Markus
Merge branch 'master' of git://github.com/MarkUsProject/Markus
Merge branch 'master' of github.com:davidrd/Markus
Fixed issue 1405
Merge pull request #1407 from davidrd/issue-1405

Closes #1405: input and animation lag on spreadsheet
Submitted code will now be sanitized for HTML before being displayed
Merge branch 'master' of github.com:MarkUsProject/Markus