Set Name field also for subtasks

[torydebra]

At the moment it seems that the name of the subtask cannot be changed and it is always the key of the yaml

For example:

RightArm:
    type: "Cartesian"
    name: "right_arm"
    #distal_link: "arm2_8"

RightArmLinear:
    type: "Subtask"
    task: "RightArm"

Results in having the topics :

/cartesian/right_arm/***
/cartesian/RightArmLinear/***