Merge pull request #1508 from chriscct7/master

Fixes fatal error in system info
Remove duplicate required fields email check
Removed ending comma
Merge pull request #1510 from sumobi/master

Remove duplicate required fields email check
Simplify edd_calculate_tax() function
Fix formatting of edd_calculate_tax()
Merge branch 'master' of github.com:easydigitaldownloads/Easy-Digital-Downloads
Fix formatting of edd_calculate_tax()
Move cart fee functions below cart total / cart amount functions
Add comment about needing to deprecate edd_get_cart_amount()
Fix 100% discount bug with taxes. #1505
Add for attributes to all labels and ID's to all inputs

Lot of labels are missing `for=` attributes, which they really should have.
Merge pull request #1512 from jdevalk/patch-1

Add for attributes to all labels and ID's to all inputs
Fix undefined index on  when not using variable prices. #1478
Fix price option storage bug with PayPal buy now buttons. CLoses #1478
Merge branch 'master' of github.com:easydigitaldownloads/Easy-Digital-Downloads
Complete string checks for cart/checkout forms. #600
Completel test_downloads_query() test. #600
Complere test_receipt_shortcode() test. #600
Add test_profile_shortcode() test. #600