Fixed bugs and turned again to runnable state

1. Added try/catch blocks to functions createMatt and getMatt, to avoid
compilation error
2. Added parameter "targetEntity" of @ManyToOne annotations
3. updated PersonEntity class
4. added constructor to SocialNetworkEntity class
5.  copied again common package "mat" to project, because Spring's
application context doesn't see classes and interfaces from other
project even if it is "Buildpathed" .