Common:
- reorganized Database API to enable extension of Context API with entities (e.g. Service)
- solved minor bugs in Database API

Context and Device services:
- rearranged services and unit tests according to mentioned Context API changes

Service service:
- initial release (under development, this is just a backup of code)

Common:
- renamed report_coverage.sh script to report_coverage_all.sh

Common/DatabaseAPI:
- improved root class validations and test units
- added _RootEntity interface
- improved definition of Context database API entities

Context service:
- added AddLink/DeleteLink rpc methods
- temporarily disabled integration tests

Device service:
- applied renamings in service and test units

Common:
- implemented ServiceException class
- updated attributes in entities belonging to Database API
- implemented test method to populate database with example topology

Context service:
- updated genproto script
- implemented report_coverage_context script
- moved specific rest scripts to root folder
- minor arrangements in ContextClient
- updated proto python files
- implemented GetTopology RPC functionality
- implemented unitary testing for GetTopology

Device service:
- updated genproto script

General changes:
- implemented data type checker class
- improved database Entity/Collection/Attributes API
- implemented grpc message parsing assertions
- integrated code coverage analyzer and reporter with code testers
- added example topology NSFNET

Common to device & context services:
- improved database context API and its tests

Context service:
- updated context proto file: added AddLink/DeleteLink RPCs, added LinkId to Link
- minor changes

Device service:
- implemented device service functionality
- improved device client
- updated genproto script
- updated device proto file: configure request becomes a Device message
- updated context proto file: operational status: added KEEP_STATUS, changed DISABLED
- moved device tests to global scripts
- extended unitary tests
- temporarily disabled integration tests

- definition of context API
- implementation of inmemory and Redis backend engines
- implementation of unit tests for both engines