Made $alert variable more extensible through use of apply_filters() function

This allows the html markup to be altered to developer's liking, as well as the actual alert message text, including CSS class names that need to be modified or added to.
Added else condition to set $first name and $last name to nothing

Fixes 2 Undefined variable notices and "cannot modify header information" warning
Initial export classes
Moved export classes to admins/reports
Ensure no timeouts
Finished first version of EDD_Export class
Include new export classes
First pass at customer export
phpdoc the customer export class
Removed old customer export code
Added the EDD_Payments_Export class
Filter on the email template
Pass the payment id on this template filter
Filter on email subject
Efficient edd_email_template_tags
Better filter readability
Ignore Phpstorm project folder

added a rule to gitignore for PhpStorm projects
fixed markup for receipt tables

added a thead element to edd_purchase_receipt table
added a tr element to edd_purchase_receipt_products table
code formatting for shortcode-receipt.php

formatting and indentation to WordPress coding standards
Merge pull request #796 from Geczy/master

Email filters