SPIMAcquisition: Allow data 'tag' customization

By request, the user can now specify a prefix for the data. This should
help differentiate datasets, i.e. by specifying date/time or other
information.

Signed-off-by: Luke Stuyvenberg <stuyvenberg@wisc.edu>
SPIMAcquisition: Add step size controls

By request, the user can adjust the step size for increment/decrement and
shift+click on three translational stage sliders. Single-step is usually
very fine, and shift+step is usually quite coarse, so the ability to
control these should help.

Signed-off-by: Luke Stuyvenberg <stuyvenberg@wisc.edu>
fixup! Converted abstract base devices into generics

Signed-off-by: Luke Stuyvenberg <stuyvenberg@wisc.edu>