Fall back to older `signature` like functionality for older versions of Python

[mandli]

PR #136 introduced some improvements to runclaw and data.py that are not backwards compatible with older versions of Python. It looks like there is not a clean way to do this so we will have to add some version checking to see what version to use.

[mandli]

This is fixed in branch. This branch still needs to deal with issue in runclaw as well. @bolliger32 we should also look at runclaw to figure what needs to be made backward compatible.

[bolliger32]

@mandli Is there more to runclaw that needs to be made backward compatible? Or did you solve it with PR #136. Couldn't quite tell from the above.

[mandli]

I think that branch has it (mentioned above). Otherwise PR #138 has everything.

[bolliger32]

got it. Looks good to me!