SAN FRANCISCO (Reuters Life!) - The Grateful Dead, the San Francisco cult rock band that has played at political events since the 1960s, will reunite on Monday for the first time in four years to rally support for Democratic presidential candidate Barack Obama, a spokesman said on Friday. Band leader Jerry Garcia died in 1995. Surviving members have played together occasionally since then, most recently in 2004. On Monday, original members Mickey Hart, Phil Lesh and Bob Weir will play at a San Francisco theater a day before California's primary. "They have agreed to reunite for this one-time-only event in...