Integrate Spotbit as a Specter Plugin

[ahv15]

Integrate the necessary components from Spotbit to allow users to use exchange rates from a local cache instead. This PR involves the following:

• Update the local cache on a regular basis.
• Fetch and store historical price exchange data.
• Configuration page for the user to choose currencies, exchanges, frequency of historical data and so on.
• Status page for the user to view whether data has been completely collected or not and make updates based on that.

To test the current progress, try accessing the endpoints. For example (http://127.0.0.1:25441/svc/spotbit/now/usd/bitstamp and http://127.0.0.1:25441/svc/spotbit/hist/usd/bitstamp/0/1658843400000)

[k9ert]

I got:

                You have an inconsistent project file-layout in folder
                /home/kim/src/spotbit
                Either you:
                * Have a src-folder and you can have .py-files in your projectroot OR
                * you don't have a src-folder but ./extensionid/service.py (+ __init__.py)
                But not having a ./src-folder AND some .py-file in the project-root is not allowed.

Anything special to get the project up and running?

[moneymanolis]

Plugin discovery didn't work for me with this version. Use the latest?

[k9ert]

Demo Video available here: https://www.youtube.com/watch?v=cNcQ1-ccedI