Refactor and fix code for export of answer statistics (!54) · Merge requests · ARSnova / ARSnova Mobile

Make use of existing download method
Use Papa Parse library for CSV generation
Remove additional header line for question subject and text (lead to inconsistent column count)
Use date and time instead of question's subject and text for file name generation (they might cause problems)
Consistently use Sencha's model methods for field access

This fixes export problems with special characters in user content. Additionally, i18n has been improved.

Refactor and fix code for export of answer statistics