Content migration by adding responsive wrappers to Iframes MIL-274, MIL-381, MIL-380 \

Activities involved in this commit 

1 . Created a new branch called "content-migration"
2 . Migrated content and dynamic content by adding responsive wrappers around Iframes
3 . Created a new scss file called iframe.scss which has videowrapper styles defined in scss , to make iframes responsive 
4 . Changed main.scss to import iframe.scss file