remove the 'network' property for platform ports to reflect corresponding removal in the CI-OMS interface specification. Related Jiras: OOIION-968, OOIION-1495.

Usual tests ok, except ion.agents.platform.rsn.test.test_rsn_platform_driver, which has already been failing apparently upon previous changes related with OOIION-1495 (still under investigation)
Merge pull request #1588 from carueda/OOIION-1564_rebase2

fix OOIION-1564 remove the 'network' property for platform ports