ref https://github.com/stack-of-tasks/sot-core/issues/58

All the work (using boost::assign) was already done.
This commit is just making sure that it compiles in 16.04 LTS.

[common] Fix bug in conversion of velocities from SoT to urdf format (base velocity is expressed in local frame in Pinocchio). Add output signals for foot vel/acc.

[balance-ctrl] Add input signals for reference contact forces and, if they are plugged, use them to determine contact phase. Remove useless assert.

[balance-ctrl] Remove urdf file name from init command input parameters (the urdf is retrieved from the ctrl manager now)

Conflicts:
	src/inverse-dynamics-balance-controller.cpp

Add support tsid.

[inv-dyn-balance-ctrl] Fix bug in computation of contact force at left foot. Minor changes to indentation.

Fix creation of RobotUtil outside of control-manager.
Fix unit tests (wrong orientation)

Reflects the new organization on the entities.

Makes RobotUtil shareable across several classes.
Implements the initialization of RobotUtil in controller-manager.
Implements ForceUtil and ForceLimits
Implements display for ForceUtil, ForceLimits, and RobotUtil.
Access to the subsequent commands can only be done after entity initialization.
Changes should be reflected on the other entities.

[balance-ctrl] Add foot task when a contact constraint is removed. Add trajectory generator for SE3 (even though the orientation part is not working yet.

[BalanceController] Create fixed-size QP solver to use for standard case (i.e. 60 variables, 36 equality constraints and 40 inequality constraints), which corresponds to modeling only the friction cone inequalities when the robot is standing on both feet and controlling only the leg joints.