Switch to images for teams

[akc42]

I think it is better (especially for caching) to store the team icons as static images.

• turn team gif files into png images in app-inmage #25 go through existing images and turn them into png files stored in client/appimages/teams with just tid as their basename
• Change existing client code to use team images rather than data from database #26 fix code in client to use image files rather than database data
• fix api calls on server to remove returning logos #31 fix api calls on server to remove returning logos
• fix database conversions to remove logos entirely (we will solely reference via tid) #30 fix database conversions to remove logos entirely (we will solely reference via tid)