Testing framework: support for extra arguments in node startup

[paolocappelletti]

In the testing framework the extra_args parameter is declared but not handled in the method start_sc_node() here: https://github.com/HorizenOfficial/Sidechains-SDK/blob/b6b533ee909db603136d3c7e2f598d1f75faa5e4/qa/SidechainTestFramework/scutil.py#L340

could be useful if we have to pass custom system properties to the node with -D option Note: as temporary solution I tried to include the -D option in the "binary" argument: this works but does not support values with spaces , as they cause a wrong split of the command line here: https://github.com/HorizenOfficial/Sidechains-SDK/blob/b6b533ee909db603136d3c7e2f598d1f75faa5e4/qa/SidechainTestFramework/scutil.py#L358

[i-Alex]

@paolocappelletti is it still a case?