Add support for DEV.to articles

[sleepyfran]

Now that #4 has been fully implemented, this will be easy to do.

Using their nice articles API (https://dev.to/api/articles/?page=1) we can get a list of the most recent featured articles and even filter by tags by specifying the tag query, with that list we can fetch an individual article specifying the ID of such article: https://dev.to/api/articles/{id}

Steps to implement this:

• Add dev.to to the services list in service-connector.js (just uncomment the line).
• Create a dev.api.js similar to the existent Reddit API; this will be in charge of fetching the articles.
• Create a dev.adapter.js similar to the existent Reddit adapter; this will transform the Dev.to response to a format that the app can understand.
• Create a dev.connector.js that calls the dev.api.js.
• Add the Dev.to case in getConnectorForCommunity.
• And of course, make a test case for the adapter similar to the existent Reddit one ;)

[sleepyfran]

Implemented in 3655ddcd2b436cca044cb5dd0708cdcd7f0421aa.