This patch adds support for short options in the eunit provider.

To prevent future mistakes like the broken string introduced in
cf66dfd6ba, put opening and closing " on separate lines in each
multi-line lopts string. This also allows for cleaner (smaller) diffs
when removing/adding a flag.

cf66dfd6ba introduced a syntax error in the modified lopts string.
Without the fix, you'll provoke a shell error when trying to complete
`rebar3 ct --<something>`.

Issues formerly were avoided by quoting atoms. Unquoting them created
unbalanced tags (`{{{name}}`) which were mistakes. This patch inserts
spaces to unconfused bbmustache.

hex.pm is now using maintainers instead of contributors in metadata.
Templates should be updated to reflect it.

Some templates like OTP apps are usable within releases, so the text
does remain a bit vague, but hopefully less than before.

- The OTP app template now adds the supevisor
- The default apps_dir value does not contain the trailing '/' that the
  template index already added.

The first variable can be unkeyed and the provider will sub in the
variable name 'name'. Additionally, the built-in templates and
documentation have been updated so that 'appid' is now 'name' and the
alternative commands are shown.

This totally breaks compatibility with rebar2, and maybe it shouldn't
have.