INSIGHT-Tax exemption may be key to move of Keurig's coffee buying to Switzerland

(Adds graphic link) By Luc Cohen NEW YORK, Sept 8 (Reuters) - When Keurig Green Mountain Inc said last December it was shifting its coffee buying operation to Lausanne, Switzerland from its headquarters in Waterbury, Vermont, it said the move would establish the company as a "global beverage player." The seller of brewing machines and single-serve coffee pods said nothing about a little-known exemption in the U.S. tax code that for many years has benefited Starbucks Corp and oth