removed --log-level due to overlap with how --verbose works now.
for consistency, added --info as alias to --verbose (as the effect is
setting INFO log level).
also added --debug which sets DEBUG log level.
note: there are no messages emitted at DEBUG level yet.
WARNING is the default (because we want mostly silent behaviour,
except if something serious happens), so we don't need --warning
as an option.
README.rst (shown on github and also at the start of the html docs) shall
be like an elevator speech - convince readers in a very short time.
this is most important, everything else can come after we got the reader's interest.
include README into docs to avoid duplication.
also include CHANGES into docs.
add developer docs, move examples from tox.ini there
add separate support docs
remove glossary, most of what was there can be understood by an admin from context
move attic and compatibility note to the end
