Ewoks json representation change

1. The graph attributes should have an "id" and a "label" instead of a "name"
2. The node attributes should have a "label" in addition to the "id"

Id's are unique, labels don't need to be unique.

Currently ewoks restricts the value of an "id" to be a hashable, which is a resitriction that comes from the networkx library

>>> import networkx as nx
>>> G=nx.Graph()
>>> 
>>> G.add_edge([1],[2])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/users/denolf/virtualenvs/ewoks/ubuntu_20_04/py38/lib/python3.8/site-packages/networkx/classes/graph.py", line 879, in add_edge
    if u not in self._node:
TypeError: unhashable type: 'list'
>>> 
>>> G.add_edge((1,),(2,))

@payno @koumouts @svensson Let me know if you have other requests concerning id's and labels.