De-dupe discovered devices/resources about iotivity-node

[ibelem]

Update: Dev will not fix this right now, will define the APIs and implement them

[gabrielschulhof]

Actually, I just realized the root cause. It requires the followings:

1. The client and the server are running on the same machine.
2. The machine on which they are running has multiple network interfaces.

In this case, devices and resources will be discovered multiple times, resulting in duplicate events.

Thus, if you leave a total of one interface up on the test device, this error will go away.

Still, I believe this should be fixed in the higher-level API implementation, and it can be fixed, but we must be able to compare discovery handles.

[gabrielschulhof]

I think I'll change the test to de-dupe the incoming events, unless we decide that we wish to address this corner case in the implementation.

[wanghongjuan]

Hi, @gabrielschulhof this issue doesn't reproduced on Joule 570x with image#191, but it is still exists on Galileo with image#508 and Joule with image#190. It is confused me, because the iotivity-node version is 1.1.0-4 on image#190/191, so I compare the difference between image#190 and image#191, there is a new commit d216381 added into image#191, could you help to confirm this issue whether is relevant with the commit? If no, why this issue doesn't reproduced on image#191?