Include data providers not from AWS and with more generic file structures

[javiquinte]

We tried to incorporate buckets from Geofon in the configuration (YAML) and modified the code to allow more generic fiel structures. For instance, SDS structures used by SeisComP.
Path and file name are merged into only one entry in the configuration.
Event bucket is optional. Root directory for waveforms can be absent if the structure starts exactly in the root of the bucket.
The method to download only one file expects to receive a file name (literally). From this file name it will infer all the components (NSLC, start, end) and create the full path based on what is declared in the configuration.

[elidana]

thanks a lot @javiquinte , this is amazing!! It is great to see that the software @pasansherath wrote can be extended to GFZ miniseed data holdings as well, so we really appreciate your contribution!

Before we can review this, do you mind please squashing all the different commits into one ? Thanks a lot in advance!

[pasansherath]

Hi @javiquinte thanks for your PR and the improvements. I have gone through your changes and tested them. It works fine with client.get_waveforms() with the client as GFZ. However, the client.read() fails due to a file name parsing error as the location codes for the GFZ miniseed files can be empty.

The function that fails is _parse_mseed_filename(filename, mseed_format) and requires some tweaking for this to work. Is this something you could look into? Thanks!