Whitespace and code formatting fix

Nothing really changed
Move mailinfo filter before storing data in db
Add hooks to add extra columns in display log screen

Fix #9
Replace deprecated `wpdb->escape()` with `esc_sql`
Make `admin_page` variable public

So that it can be accessed from addons
Add information about Pro Addons
Bump version number to v1.5.2 for release
Regenerate pot file for translation