Selection of appropriate grasping strategies for different objects

[alex-mitrevski]

Our existing pickup action treats all objects equally, i.e. we don't have runtime selection of object-specific grasping strategies. The pickup action client should thus be modified so that an appropriate grasping strategy is selected depending on the object category. In the long term, the purpose for which the object is grasped should also be taken into account.

The resolution of this issue is contingent on b-it-bots/mas_knowledge_base#14