Added capabilties as arg to move_group.launch

[agutenkunst]

Enable the user to pass capabilities that should be loaded / inhibited
as arg to move_group.launch

Description

I ran into the issue because I wanted to load capabilities into the move_group from another package.
Without this PR I would need to duplicate the move_group.launch file.
Passing it as an arg is the same way the other args are handled.

[v4hn]

I do not really see the necessity for this.
You can always set

<rosparam name="move_group/capabilities">
my_awesome_capability
</rosparam>

The move_group namespace is pretty much enforced in MoveIt, so there is not even a problem with node renaming.

Wouldn't you agree?

[davetcoleman]

interesting workaround @v4hn

[v4hn]

Looking at this again, there is also no harm in having the arguments there. Maybe it makes things a bit clearer in custom launch includes...
I approve as is.