Due to a build problem with the reactive plugin, this change falls back
on overriding the steps and doing a manual build, but it also ensures
the CI system builds the charm using charmcraft. Changes:
- add a build-requirements.txt
- modify charmcraft.yaml
- modify osci.yaml
-> indicate build with charmcraft
- modify tox.ini
-> tox -e build does charmcraft build/rename
-> tox -e build-reactive does the reactive build
- modify bundles to use the <charm>.charm artifact in tests.
and fix deprecation warning re: prefix
- tox inception to enable tox -e func-test in the CI
Change-Id: I1bbdebb22fcd6cac4ceae74d90d70a8d94f3c769