Add @Override toString() in InstanceInfo

[phantasmicmeans]

Application(class) can get simple information by @OverRide the toString().

-> toString() in Application.java

@Override
public String toString() {
    return "Application [name=" + name + ", isDirty=" + isDirty
            + ", instances=" + instances + ", shuffledInstances="
            + shuffledInstances + ", instancesMap=" + instancesMap + "]";
}

It is simple to use some information immediately.

But What is more necessary is the information in InstanceInfo(class)?
InstanceInfo provides a detailed information about the eureka client.
InstanceInfo provides a getter, but it has about 30 member variables.

So it seems necessary to provide the overriden toString() of InstanceInfo