Revert "Fix up issue with preview."

Necessary component to generating preview links for posts with custom statuses

This reverts commit ac462ad13815a0152566b8b5454ac805b96c2536.
Remove unused third argument
Consolidate this code to a common method
Fix error notices created from typo in variable

See #227
Merge pull request #227 from Automattic/fix-notice-227

Fix PHP notice: Undefined variable: wp_post_statuss
Merge pull request #226 from Automattic/fix-preview-link-226

Preview link broken for posts assigned a custom status
Add a check to determine if the url has already been formatted. This is necessary for versions of WP > 3.5, which applies preview_post_link to the url created by the post_preview function in core.