Make the Conda-Forge package production-ready

[Zeitsperre]

Raven-WPS is now on conda-forge (https://github.com/conda-forge/raven-wps-feedstock), but this package is very beta, alpha even. There are a number of issues that need to be addressed:

• Flesh out the CLI - Given that we rely on the Makefile for deployment, we need to integrate some Runtime configurations into the CLI of the tool (we should be doing this anyway). We should be able to Raven-WPS from the command-line, asking that users provide a configuration file when called if they don't want the default run configuration.
• Renaming Raven-WPS - There's also the issue of the shared utility name between Raven-WPS and Raven-Hydro. On the command line, the raven-wps package is called using $ raven-wps, whereas raven-hydro uses $ raven. We should update our documentation and deployments to use the new name when we're ready.
• Fixing GDAL - There's always the annoyances from GDAL: As it stands, I've hard-coded Raven-WPS to use conda-forge-provided gdal ==3.4.0. There are two means of fixing this:
  • Use build variants (https://docs.conda.io/projects/conda-build/en/latest/resources/variants.html) to allow a few specific versions of GDAL to be supported (lots of redundancy, needs to be rebuilt from time to time with newer GDAL versions).
  • Specify in the recipe for the requirements stage that the build and run dependencies for GDAL must be using the same version (https://docs.conda.io/projects/conda-build/en/latest/resources/define-metadata.html?#export-runtime-requirements). This is a common approach for linking C++ libraries (but none of the methods I've tried have worked so far).
    • Dealt with in Update recipe for v0.15.1 conda-forge/raven-wps-feedstock#2