dev: factor out duplicated rcov invocation
fix ./dev run-unit-tests to work with simplecov
dev: add run-tests and run-BDD-tests subcommands

The run-unit-tests subcommand was a misnomer, because it also
ran BDD tests.  Now the names reflect the actions accurately,
and it's also possible to run only unit tests, or only BDD tests.
doc/devguide/testing/devtool.md: improve Ubuntu instructions
dev: rename {setup,reload,clear}-unit-tests subcommands

These commands were also misnamed, because they relate to the
whole test environment, not just unit tests.
dev: fix setup-test-env subcommand option handling

- remove final remnants of old setup-unit-tests --offline option
- add missing documentation for --no-gem-cache
dev: fix syntax error in run_unit_tests()
dev: avoid an error if chef/cookbooks/README is missing
dev: remove misleading reference to rcov when running Chef specs
doc/devguide/testing/devtool.md: add openSUSE instructions
doc: move CLA information into a separate page
doc: add new contributor's guide page
move dev-setup/ docs to doc/devguide/
devguide/barclamps: fix typo and tweak wording
devguide: add technical topics to index
devguide/testing: much refactoring and editing

- improve wording
- add links
- new BDD and web UI pages
- remove duplicate information

and more ...