document generation for vouchers

There is possibility to "print voucher" by having a .docx template that is in Voucher scope.

On subject page there is possibility to print selected vouchers (selection is done by checkboxes). In such situation all selected vouchers will be applied to all possible voucher templates and this data will be merged into single docx file.

Closes #196 (closed)

added 8 commits

• 0bd6e0d2 - voucher partner is obligatory in voucher, voucher number is generated using schema
• 715564e8 - single voucher can be used in few sessions at voucher partner
• 4f128a8a - notification about future voucher expiry date starts 7 days before expiry date
• 56ed2f9b - voucher will expiry after 90 days
• ee86c08d - voucher context added to document generation
• 5e377687 - document generation is allowed from voucher edit page
• f694d253 - method for merging docx files
• b1dfc149 - there is a way to print selected vouchers

Compare with previous version

unmarked as a Work In Progress

changed title from WIP: Resolve "document generation for all vouchers" to document generation for vouchers

changed the description

assigned to @valentin.groues

merged