Add convention version to INTERFACE

[irm-codebase]

Added convention_version to INTERFACE.yaml.

Things to note:

• REGEX for semver is enforced, with the caveat that 'v' prefixes are accepted (e.g., both 1.0.1 and v1.0.1 are accepted).
• clio_tools will see any valid semver string as valid. For now, clio_tools does not see as its job to reject or accept any version.
• This is only to allow quick dismissal of unsupported versions by other tools (i.e., the Modelblocks website, automated parsers, etc).

Also, I removed some shapefiles that were in this repo. They were leftovers from ec_modules.

[jnnr]

Looks good, only minor comments. Could show all fixtures together for readability, but not pushing for it.