make 'preapproved' payments get same access rights as 'complete' payments

This small tweak seems to address what I brought up in [issue #1232 for EDD](https://github.com/easydigitaldownloads/Easy-Digital-Downloads/issues/1232)
Fix [download_discounts] invalid argument warning.

An invalid argument supplied warning is thrown when there are no
discounts.
Fix empty [download_discounts] invalid argument warning.
Merge pull request #1238 from fxbenard/master

[i18n]> update translations files after commit #1236
Fix duplicate action hook name
Fixed conflicts
Merge branch 'master' of github.com:easydigitaldownloads/Easy-Digital-Downloads
remove 'preapproved' getting same access rights as 'complete' payments
use media_buttons action instead of media_buttons_context filter for "Insert Download" button
Fix undefined inde
Merge branch 'master' of github.com:momnt/Easy-Digital-Downloads into momnt-master
Fix relative path for X-Accel-Redirect. Closes #1245
Restore headers for #1245
Changes eqality operator to identity operator. Fixes #1246
Merge pull request #1247 from embolden/master

Changed the equality operator to identity. #1246
Move purchase receipt sending to edd_complete_purchase
Update priority to 999 for email receipts
Merge branch 'master' of github.com:easydigitaldownloads/Easy-Digital-Downloads
Add filter for template tags description
Merge pull request #1249 from ghost1227/master

Added filter for template tags description