Add team logos spritesheets

Two sizes of spriteshees available with 23x23 and 30x30 logos.
Team has new method, logo_html(size). If the size requested is available as a sprite, returns html for the sprite. Otherwise returns standard img tag with the url for SI's CDN.
User has new method, name_with_flair(size) which uses team's logo_html method to generate flair followed by nickname.
Replace all instances of logos with new methods.