(Matthew Swift reviewed) Code cleanup.

OperationWrapper.java:
Generecized the type of the wrapped operation.
Added protected method getOperation() that returns the wrapped operation.

AddOperationWrapper.java, BindOperationWrapper.java, CompareOperationWrapper.java, DeleteOperationWrapper.java, ModifyDNOperationWrapper.java, ModifyOperationWrapper.java, SearchOperationWrapper.java:
Added the generic type to the superclass OperationWrapper.
Got rid of specific instance members to old the operation with the correct type and called getOperation() instead.