Analyticity of layer potentials and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"><mml:msup><mml:mi>L</mml:mi><mml:mn>2</mml:mn></mml:msup></mml:math> solvability of boundary value problems for divergence form elliptic equations with complex <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si2.gif" overflow="scroll"><mml:msup><mml:mi>L</mml:mi><mml:mo>∞</mml:mo></mml:msup></mml:math> coefficients