Remove warnings_as_errors for the sake of Erlang 21.x

[jonasrichard]

Since ssl:ssl_accept is deprecated chatterbox cannot be compiled as a dependency because of this.

https://github.com/joedevivo/chatterbox/blob/master/rebar.config#L5

It would be a good idea to either remove this compile option or use ssl:ssl_handshake (I don't know how difficult it is).

[ferd]

As a workaround, using the latest rebar3, you can use:

{overrides, [
    %% For all apps:
    {del, [{erl_opts, [warning_as_errors]}]},
    %% Or for just one app:
    {del, one_app, [{erl_opts, [warning_as_errors]}]}
]}.

to work around it if using this app as a dependency.

[tsloughter]

I fix this in my PR #127 with macros so that it just depends on what OTP you are building against for which it uses.

Just waiting to get it fully reviewed before merging.

[varoun]

As a workaround, using the latest rebar3, you can use:

{overrides, [
    %% For all apps:
    {del, [{erl_opts, [warning_as_errors]}]},
    %% Or for just one app:
    {del, one_app, [{erl_opts, [warning_as_errors]}]}
]}.

to work around it if using this app as a dependency.

The correct override is as follows:

{overrides, [
    %% For all apps:
    {del, [{erl_opts, [warnings_as_errors]}]},
    %% Or for just one app:
    {del, one_app, [{erl_opts, [warnings_as_errors]}]}
]}.

Basically, s/warning/warnings/ ... This tripped me up.