sMOMENT with MitoCore

We adapted some parts of the autoPACMEN library to work with our workflow for the sMOMENT model.

• removed the _cache directory, as some of the filenames can cause trouble with windows fil system
• changed the SABIO-RK API url to use "https"
• added a module for determining sensitivities of the FBA objective function with respect to the kcat values
• ignore if GPR list in get_initial_spreadsheet is empty for complex GPRs