Fix all the scripts

[varunagrawal]

Fixed some scripts which were broken because of mine and Frank's previous PRs.

Basically, I had to initialize the prior joint angles, velocities and torques.

[gchenfc]

It's been a long time since I worked on this codebase, but would utils/Initializer::ZeroValues work here?

[varunagrawal]

I thought about that but ZeroValues adds initial values for a lot more things (like twists and wrenches in the workspace). On further thought I think the overhead is worth it though, so let me update it.

[varunagrawal]

@gchenfc gentle reminder