Add stackoverflow service

[bikrambhattacharya]

Need to add Stackoverflow service.

When someone types ~sof search_query it should show the search result.

[vicky002]

Any update on this @bikrambhattacharya ?

[bikrambhattacharya]

@vicky002 Working on this will update progress detail by tonight.

[bikrambhattacharya]

@vicky002 80% done for rest 20% need your help please check slack DM