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
Add the new tax settings
Working tax displays + calculations
Payment confirmation displays
Two helper tax functions
New super useful edd_is_taxes() function
Phase out edd_taxes_on_prices()
AJAX tax opt in, currently its delayed but a start
Convert tax cookies -> sessions
Just get the taxes