Fixes #354 as per TAPI 10/02/2018 call discussions

[karthik-sethuraman]

Fixes #354 as per TAPI 10/02/2018 discussions

• Maintenance Entity has been removed
• OamService will specify at least 2 OSEPs which has provisioning info for either -- 2 MEPs (OamService represents an MEG wholly contained in the domain) -- 1 MEP & 1 MIP (OamService represents a segment of a MEG in an edge domain) -- 2 MIPs (OamService represents a segment of a MEG in a transit domain)
• OamJob will specify at least 1 OSEP which points to an MEP
• OSEPRelatesToMEP/MIP association navigability changed to one-way from OSEP to MEP/MIP
• Added mepIdentifier and peerMepIdentifier attributes to OSEP
• Added mipMac & isFullMip attributes to Eth augmentation of MIP