Test system uses configfile

Checklist

• I have read the contribution guidelines.
• Unit tests have been added for any new or changed code, and the test suite passes. Note: Your request will likely not be merged without the appropriate tests.
• "closes #XXXX" is in the body of the MR description to link the related issue, if applicable.

• The test suite now reads the user's configfile in order to get executables, then loads the ase-datafiles data paths (expressed as another configfile) and overrides the production pseudopotential paths.
• Calculator factories are updated so as to work in terms of profile objects where possible/easy