CHICAGO (Reuters) – The sign at the entrance to President Barack Obama's new 2012 campaign headquarters says: "Respect. Empower. Include. Win." A swarm of reporters got a sneak peak at the Obama's headquarters on Thursday at a downtown Chicago office building. The 50,000 square-foot space occupying a full floor of the building, is mostly open except for rows of tables sparsely populated by roughly 50 staffers and volunteers. The number of campaign operatives will be increased during Obama's re-election bid and Campaign Manager Jim Messina and other operatives said the space's organization reflects Obama's grassroots campaign style, which is open...