add properties to exclude in Entity->toArray() method 

(as a result of upgrade to Doctrine 2.4, probably)

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | na
| Fixed tickets | na
| Refs tickets  | na
| License       | MIT
| Doc PR        | na