Change in behavior with new definition of Elie's model CompositeBloxs

[gabrevaya]

With this change 4e56aa6 in src/blox/DBS_Model_Blox_Adam_Brown.jl I'm getting different firing rates than those obtained when using the previous version.

For example, for MNS-FSI network in baseline condition, with the previous version I got

MSN mean firing rate = 1.90 ± 0.06
FSI mean firing rate = 10.59 ± 0.03

while with the new version:

MSN mean firing rate = 1.58 ± 0.11
FSI mean firing rate = 14.61 ± 0.09

I'll write a MWE soon. We may change this file back to its previous version at least for the tutorials and later find proper fix.