Added Debounce support on value changes

Needed to debounce the input changes, otherwise multiple quick changes will update the placeholder tag src repeatedly, firing multiple HTTP requests to the Video Placeholder Generator Server

CSS Bugfixes

Thumbnail image would escape the bounds of its container if it was sized too large. Fixed by using flex.

First major release

Separated the server-side functionality into its own repository: https://github.com/MissionMike/Video-Placeholder-Generator-Server

Since client-side functionality is not wholly dependent on the server-side, and they use different development environments (ReactJS on front, PHP on back), it seemed ideal to split the repo, so they can both be developed more independently of each other.

UI is improved, additional options added and works in tablet/mobile.

Initial release

Initial release with working UI and functional back-end. Needs tons of improvement, but here's a start!