adapt component parser to new xml schema

[Karsten1987]

addresses the concerns raised in ros-controls/roadmap#28 (comment)

[bmagyar]

One minor comment, otherwise looks good to me!

[codecov-io]

Codecov Report

Merging #209 into master will decrease coverage by 20.88%.
The diff coverage is 32.42%.

@@             Coverage Diff             @@
##           master     #209       +/-   ##
===========================================
- Coverage   36.61%   15.72%   -20.89%     
===========================================
  Files          42      116       +74     
  Lines        1726     9066     +7340     
  Branches     1080     1880      +800     
===========================================
+ Hits          632     1426      +794     
- Misses        100     5973     +5873     
- Partials      994     1667      +673     

Flag	Coverage Δ
#unittests	15.72% <32.42%> (-20.89%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...r_manager/test/test_controller/test_controller.cpp	100.00% <ø> (ø)
...r_manager/test/test_controller/test_controller.hpp	100.00% <ø> (ø)
...e/include/hardware_interface/actuator_hardware.hpp	100.00% <ø> (ø)
...hardware_interface/actuator_hardware_interface.hpp	100.00% <ø> (ø)
...ce/include/hardware_interface/components/joint.hpp	100.00% <ø> (ø)
...e/include/hardware_interface/components/sensor.hpp	100.00% <ø> (ø)
...re_interface/include/hardware_interface/handle.hpp	73.33% <0.00%> (-5.24%)	⬇️
...ace/include/hardware_interface/sensor_hardware.hpp	100.00% <ø> (ø)
...e/hardware_interface/sensor_hardware_interface.hpp	100.00% <ø> (ø)
...ace/include/hardware_interface/system_hardware.hpp	100.00% <ø> (ø)
... and 104 more

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[bmagyar]

Have you updated the urdfs by hand? Please update the example URDFs from the example URDFs page we have here: https://github.com/ros-controls/roadmap/blob/master/design_drafts/components_architecture_and_urdf_examples.md

Using min_position_value has been gone for a while and should be updated.
I saw that some asserts were removed due to this, please re-add them.

[bmagyar]

@Karsten1987 happy to go ahead with this once the CI is happy. I can do a follow up update of the example urdfs provided there is an issue for it.

[bmagyar]

As per #214 I'm ignoring the foxy source job on this one. @Karsten1987 let me know if you are happy with the changes I put on top and if yes, feel free to merge this