Merge pull request #99 from glucazeau/develop

1st merge in develop/master
Merge pull request #117 from glucazeau/develop

Merge Develop
Hide delete student button #90
Fix arrival date, not required
Fix student creation confirm message
Fix typo in class name
Remove unused getter/setter
Save country code in lowercase
Show teacher who welcomed the student
Do not set registration date to the current date on student creation
Show arrival date if not empty
Do not display birthdate and age if empty
Fix update message on student
Fix dates display
Fixes #28
Escape first/lastname for JS #28
Fixes #73
Display different list for "my students" - Fixes #71
Hide button to create a new class #90
Set credentials expiration date when changing password