company_video field + output + new template files

Closes #239
Fix upload dir and generate attachment metadata

Fixes #249
show_more="false" for jobs shortcode to prevent loading more jobs.

Closes #250
Use absolute URL

#249
Update placeholder
Additional filters
Support HTML5 multiple attribute for file upload field. Pass multiple=>'true' to form field definition to enable.

Closes #66 @spencerfinnell @adampickering you guys may want to test
these changes.
Prevent errors with non-arrays
Allow custom settings field types

Allows custom settings fields types + has backward compatibility for settings fields without defined 'type' which falls back to text input.
Update class-wp-job-manager-settings.php
Convert categories to slugs for RSS feed.
Allow pending_payment to be approved
Merge pull request #253 from JeroenSormani/master

Allow custom settings field types
Later loading for template functions.

@adampickering @spencerfinnell this ok with you? To make them pluggable
tested to
b/w compat or settings fields
Fix action buttons for pending_payment jobs
tweak escaping
typo
add filters to geocode URL and region to allow region bias

Closes #258