Changes and Improvements

Change:  The translations file names was changed to follow the i18n and
i10n standards
Change: The messages in translations files was changed from constants to
a literal object
Improvement: It simplified the code that chooses the appropriate error
message for each type of error in the showError() method
Improvement: New CSS styles for the message error
Changes and improvements

Change:  The translations file names was changed to follow the i18n and
i10n standards
Change: The messages in translations files was changed from constants to
a literal object
Improvement: It simplified the code that chooses the appropriate error
message for each type of error in the showError() method
Improvement: New CSS styles for the message error