Add n_init_samples to ExpDesign constructor

Allow the user to give n_init_samples directly to the init for ExpDesign.

changed milestone to %2.0.0

added Input space label

assigned to @alacheim

Make sure that n_init_samples then gets set to the actual number of samples (X) if they are set by the user.

created branch Fix/n_init_samples_to_ExpDesign to address this issue

mentioned in merge request !50 (merged)

closed with merge request !50 (merged)