support mapping of edge attributes

[jjgao]

No description provided.

[jjgao]

Here is the link to the code repository for the Interaction Identifier mapping database : https://github.com/pennatula/InteractionDB.

The derby database file can be found here : https://github.com/pennatula/InteractionDB/tree/master/bridge

An example pathway file is also present in the same repository. It contains a single reaction at present, I am trying to come up with a better test pathway. Since the coverage of Rhea is not that extensive yet, it is turning out to be quite difficult.