Refactored and added new specs for Vertex.java

1) Combined the common part in before block
2) Added specs for - getOutgoingEdge, getIncomingEdge, getoutgoingEdgeOfType, getIncomingEdgeOfType, getIncomingSourceData
Added more specs for Vertex.java

- getIncomingSourceDataOfType
- getOutgoingDestinationData
- getOutgoingDestinationDataOfType
Merge pull request #884 from prathamesh-sonpatki/ir-specs-1

More IR Specs related to Vertex.java