Update code of conduct
Update code of conduct

The goal with this updated version is to:

  * Outline the goals for the code of conduct
  * List the values Elixir developers should aspire to
    and not only the unnacceptable behaviours
  * Be explicit about where the Code of Conduct applies and
    recommend other parts of the community to follow it

pedrosnk/elixir,kimshrier/elixir,lexmag/elixir,michalmuskala/elixir,antipax/elixir,kelvinst/elixir,ggcampinho/elixir,pedrosnk/elixir,gfvcastro/elixir,ggcampinho/elixir,gfvcastro/elixir,elixir-lang/elixir,beedub/elixir,antipax/elixir,kimshrier/elixir,lexmag/elixir,kelvinst/elixir,beedub/elixir,joshprice/elixir