Create a Rocket.Chat connector module

[jacobtomlinson]

Let's add a Rocket.Chat connector as proposed in #498.

Steps

• Make a new submodule directory in opsdroid.connector called rocketchat and create an __init__.py file inside.
• Implement the connector according to the documentation on writing connectors.
• Update the requirements.txt with any new dependencies from the connector if necessary.
• Write tests for the connector. (See the Slack connector tests for inspiration).
• Create a new documentation page.
• Add the new page to the mkdocs.yml.
• Add to the list of connectors.

Resources to get you started

• Rockat.Chat REST API
• Rocket.Chat Beta Realtime API
• jadlog/rocketchat_API (bear in mind my comments in Connector request: RocketChat #498)

Asyncio

Opsdroid uses asyncio and an event loop, so here are some things to bear in mind:

• Functions should be coroutines which are defined with async def myfunc(): ...
• Coroutines are called with await. For example await myfunc(). This is how asyncio allows many functions to take it in turns as they swap over when the current thread calls await.
• Don't block the thread! If you need to make a call to a blocking function such as time.sleep() or any kind of IO request such as requests.get() then you should await an async variant. For example you can call await asyncio.sleep(10) to sleep without blocking the whole application and you can use aiohttp as an async url library.

[FabioRosado]

I have been wanting to tackle this for a while but kept slipping my mind, so I'll give it a try 👍