- Added/Updated headers
- Added script to update copyright headers

Common:
- temporarily added backend to pathcomp service for debug purposes

Proto:
- Added KDisjointPath Algorithm to pathcomp proto

Frontend:
- refactored Servicer to cope with multiple algorithms
- added implementation of ShortestPath algorithm
- added implementation of KShortestPath algorithm
- added implementation of KDisjointPath algorithm (partial)
- moved PathComp servicer tools to algorithms subfolder
- added new unitary test scenario (DC's with CellSiteGWs and Transport Network) to validate KDisjointPath algorithm

- Added definition of algorithm in proto file
- Minor code comments and TODOs added

- extended proto file to support retrieval of both services and connections, e.g., services requested + sub-services, and the connections and sub-connections supporting the services and sub-services.
- minor bug fixings in MockServicerImpl_Context and implementation of support for Slices
- implemented and pre-tested unitary tests for PathComp
- implemented in PathComp service the logic to retrieve context data, and the skeleton to retrieve the replies to compute requests.

- initial skeleton (not functional)

- Added RequestSlice to Interdomain
- Separated Create and Update in Slice

- formatted and corrected interdomain and slice proto files
- regenerated associated Python code files per component

Policy component's protobufs are updated based upon
the Event Condition Action (ECA) model.
Minor fixes are applied to the slice.proto in order
to compile.

Signed-off-by: Georgios Katsikas <katsikas.gp@gmail.com>