Merge branch 'release/v2.5.1'
* Fix: variable name $sub['id'] should be $sub_id in admin submissions view

This error caused a PHP Notice on the admin page that lists submissions.
It was introduced with 1e39788a2ea6e21b8a3d55674924bb1731653de1
fix button close

Button close get IE 9 display error
not sending attachment parameter to wp mail when not needed
Merge pull request #198 from karimtn/patch-2

fix button close
Merge pull request #197 from NateWr/master

Fix: variable name $sub['id'] should be $sub_id in admin submissions view
applying filters to form list fields
correctly escaping form list filters
adding ninja forms get preview page title filter
adding filters for form settings
Merge pull request #204 from BFTrick/settings-filters

Adding Filters on Form Setting Page
Merge pull request #202 from BFTrick/preview-page

Adding a Preview Page Title Filter & Getter
Merge pull request #201 from BFTrick/form-list

Add Filters to Form List Admin Page
Merge pull request #200 from BFTrick/email-attachments

Email Attachments for Gmail
Default label position should be above.
Fixed some spacing issues.
Only add the required symbol after the element if the label position is not set to 'inside'.
Added a filter to the ajax url for front-end submissions.
Gave the processing message div a class of ninja-forms-processing
Changed the adding of "selected" list elements as default value to the ninja_forms_display_pre_init hook.