Acceptance strategy

First version of the acceptance strategy. The acceptance strategy ACcombi is used, this is described in "Baarslag, T. Hindriks, K. and Jonker, C. M. (2013), “Acceptance Conditions in Automated Negotiation”, Complex Automated Negotiations: Theories, Models, and Software Competitions, 435, pp. 95-111. http://ii.tudelft.nl/sites/default/files/Acceptance%20Conditions%20in%20Automated%20Negotiation-pub.pdf".