Amazon.com Inc. said Louise Erdrich’s “The Round House” is its best book of the year, beating out “The Yellow Birds: A Novel” by Kevin Powers. The Seattle online retailing giant (NASDAQ: AMZN) described "The Round House" as "Erdrich’s moving, complex and surprisingly uplifting new novel (that) tells of a boy’s coming of age in the wake of a brutal, racist attack on his mother." "'The Round House’ has been a team favorite since we first read it this past summer, and we kept coming…