Added "X-Frame-Options" clickjacking protection

https://developer.mozilla.org/en-US/docs/HTTP/X-Frame-Options
Added cryptographically secure random hash gen

This function adds a cryptographically secure method to generate random
hashes.  It can be used to replace OpenCart's use of md5(mt_rand())
which has been shown to be insecure.
Moved to cryptographically secure hashes

Select areas now use new hash_rand() function