some error messages are now emphasized
added option to delete Phd Guidance Documents
Merge pull request #580 from cbartol/ticket/rt#422187

Corrected the style of some error messages, some error messages are now emphasized
Merge pull request #579 from cbartol/ticket/rt#404219

Added option for Phd Coordinators to delete Phd Guidance Documents
close #578
Bug fix: exceptions were being silently encapsulated and leaving
inconsistent data
Minor change: allow to create a registration with no learning agreement
as long as the agreement only requires the degree to be chosen