simplify usage display

This avoids making the parameters column quite wide, which caused
descriptions of other commands to not fit in 80 cols in the usage display.

FIELD=VALUE is a simplification, but so was the old display. The man page
gives more detail.
info: When run on a single annexed file, displays some info about the  file, including its key and size.
info: When passed the name or uuid of a remote, displays info about that remote.

No per-remote-type info yet.

This commit was sponsored by Stanley Yamane.
add per-remote-type info

Now `git annex info $remote` shows info specific to the type of the remote,
for example, it shows the rsync url.

Remote types that support encryption or chunking also include that in their
info.

This commit was sponsored by Ævar Arnfjörð Bjarmason.
include creds location in info

This is intended to let the user easily tell if a remote's creds are
coming from info embedded in the repository, or instead from the
environment, or perhaps are locally stored in a creds file.

This commit was sponsored by Frédéric Schütz.
note whether or not embedded creds are encrypted
add internet archive item url to info
devblog
Merge branch 'master' of ssh://git-annex.branchable.com