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.
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
Correct tax display bug on checkout. #1239
Fix error on tax save. #1235
Add Choose to country list and allow all tax rates to be deleted. #1235
Move email template tags function to emails/functions.php. #1249
Added missing textdomain
fix typos
fix another typo
Merge pull request #1251 from sumobi/master

Fix typos
Simplfiy edd_checkout_button_purchase
Change "Purchase" to "Download" on Free Purchases
slight modification to match new github code