Events for creating FTA node are fetched incorrectly

[blcham]

When fetching Events to create a root node or any other FTA node, we use the wrong API.

It seems that faultTrees/$ftaTree/reusableEvents is used but @kostobog mentioned that different API should be used (something like /all-fault-events/$systemFragment)

Motivation here is to have all relevant events -- we want to include also SNS based events so we would be able to create SNS node. Of course for root FTA node we do not want to choose from SNS-based events.

[blcham]

@kostobog please fix/add description above.

[blcham]

FYI @LaChope

[LaChope]

@blcham If you want I can do this, I know where to update the API, just need to make sure that /all-fault-events/$systemFragment is the correct one.

[blcham]

• we need IRI of System instead of name (need BK to fix on backend first)

[LaChope]

Closing as solved by #355.