add Entities in several modules

1. add entities
2. checked schema generated with eclipselink according to entities
Notes on joins accoss composte primary key tables,especially with
following scenario:
T1.PK(TENANT_ID, ID),
T2.PK(TENANT_ID, ID)

Remember to use JoinColumn.insertable, JoinColumn.updatable attributes
to avoid multiple update capability on relationship definition.

On the other hand:
a. JoinColumns setup for ManyToOne with Composite Key. Owning Side's
TENANT_ID is maintained ONLY by the owning side table, any of the
ManyToOne relationship cannot "insert" or "update" owningSideTable's
TENANT_ID
b. JoinColumns setup for ManyToMany with Composite Key, which creates
JoinTable. ONLY Owning side maintains the JOIN TABLE's TENANT_ID.