Fixes Slow Info Retrieval Handling

PR: #4

Issue:
Sometimes the page doesn't reply with listing info fast enough and retrieveListingInfoFromPage returns null data in the promise.

Fix:
Moves the promises to a separate array that gets satisfied upon the next listing info update from the page

v1.1 - Rewrite

Thanks to @bmwalters, the CSGOFloat extension has been rewritten!

• Improves readability and extendability for the future
• Repositions "Get All Floats" buttons above the listing table