Remove deprecated methods

* Removed options: `include_ie7_css`,`use_bxslider`, `disable_animation`, `fade_out_speed`, `fade_in_speed`, `height`, `min_height`, `max_height`
* RESOLVE #112 Remove deprecated methods
* Revise widget class and files names
Remove deprecated methods

* Removed pre-2.0.0 migration code
* Removed shortcodes: `testimonialswidget_list`, `testimonialswidget_widget`
Update localization
Add shortcode testimonials_archives

* Add shortcode and theme function `testimonials_archives`
* RELATES #132 Implement shortcodes for all widgets