cli: various clean ups

move function to find the format manager for a given filename to dataio

correction report error status after --acquire and --live
cli: new small utility convert

allows to convert from one format to another

very basic, but it works. As tiff has not import ability yet, it can only do HDF5->TIFF
cli: add minus argument to convert

useful for subtracting background image, etc.
cli: clean up
add odemis-convert script to launch cli/convert.py