builder to add vimeo videos with ids of any length

https://github.com/Esri/map-tour-storytelling-template-js/issues/26

When adding a new map tour point in the builder and selecting a vimeo video, the builder only worked correctly in finding a thumbnail and video if the id was exactly 8 digits. This isn't always the case with vimeo videos. The latest videos now have 9 digits and there are even videos in the single digits. 

Made a single change in two places to allow for arbitrary length ids. I tested adding a video with 9 digits and one with 7 digits. Both worked fine. Before, the one with 9 digits would have tried to find the video related to the first 8 digits in the id and the video with 7 digits would have failed.