Merge pull request #4726 from atif-shaikh/CRM-5039

CRM-5039 - Events don't always limit registrations to "max participants"...

diff --cc CRM/Event/Form/Registration.php
Simple merge

diff --cc CRM/Event/Form/Registration/Confirm.php
Simple merge

diff --cc CRM/Event/Form/Registration/Register.php
Simple merge

diff --cc CRM/Price/BAO/PriceField.php
Simple merge