Merged in loaddistributedexp (pull request #8)

[NRPJP-83] errors in loading experiments were due to incorrectly parsing populations attached to devices. This commit fixes it.

* [NRPJP-83] errors in loading experiments were due to incorrectly parsing populations attached to devices. This commit fixes it.

* [NRRPLT-83] commented out annoying print

* [NRRPLT-83] Added suggestions from reviewer and removed unnecessary commented code

* [NRRPLT-83] Rearranged some code into a function + added function descriptions

* [NRRPLT-83] Fixed bugs introduced along PR

* [NRRPLT-83] Fixed index_from_assembly not considering that populations can be instances of Population

Approved-by: Kepa Cantero <cantero@fortiss.org>
Approved-by: Ugo Albanese <ugo.albanese@santannapisa.it>