extend worker class

Worker class should become more as a person.

There should be flag marking that worker should have access to the system.

There should be also possibility to make persons that are external doctors (HP in PDP) or partners (VP in PDP)

Person should have information:

• specialization - set of possibilities

• phone number

• phone number 2

• fax number

• address

• voucher types (for VP)

• list of patients (for HP)