Only clear our variation cache pre-3.9.
Only define DONOTCACHEPAGE as true if it is not already defined.
Avoid notices in purchase log list table by checking for the existence of the first name, last name, and email.
Fix minor doc typo.
Avoid strict standards pass by reference error.
Eliminate extra  global in save_forms_to_db() method.
Avoid notices on Purchase Log page.
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Merge pull request #1089 from JeffPyeBrook/pr-visitor-meta-cleanup-hardening

Visitor Meta Cleanup Hardening
Visitor Authentication Security Hardening

**Insipred by CVE-2014-0166 resolved in WordPress 3.8.2**
Instead of using wp_hash, a pluggable that can be overridden we use hash_hmac with a wll defined WPSC_SALT
Introduced WPSC_SALT an constant that can be defined in our config files, or takes on the value of the WordPress Authentication salt.
If the WordPress authentication salt is not available a unqiue salt is created using the file name, which should be cosntant, and the file path, which should vary from installation.to installation.

**Also...**
Removed a call to ctype, this library may not be available on all servers
Merge branch 'pr-visitor-hash-hardening' into dev-master