Update .travis.yml

Add the products of yecc and leex to the excluded_files list

Use the same versions of Erlang as the main Erlcloud project

Including these in the published Hex package makes it not work on
pre-18 versions of Erlang

Upgrade to Rebar3, additions to publish to Hex.pm

Uses rebar3 as the build tool, but with a rebar.config.script for
rebar2 backwards-compatibility.

A few bits filled in on the .app.src file for Hex.pm publishing.

Coverage XML file goes to .eunit/ directory

Binary and filename take over function to register ets table.

This fix bug of line number error.
Thanks to @Hexa.