Do not include Erlang library sources in the release

This cuts down 6 MB on the uncompressed size of the release.
Use precompiled Elixir on Travis
Merge pull request #39 from alco/travis

Use precompiled Elixir on Travis
Merge pull request #38 from alco/nosrc

Do not include Erlang library sources in the release
Version 0.11.2
Merge master