add fields; show custom post on main page; fixes

Add our custom fields to the bottom of the post content. (Todo: format
these fields.) Add our custom post type to the main wordpress page. Use
closures where possible to clean up unnecessary functions and globals.
Add "joblist_" prefix so our functions and variables don't interfere
with other plugins. Flush rewrite rules on activation. Add various todos
where appropriate. Remove template.php as it's no longer needed.