Explicit required version of exlager

Elixir 0.10.1 removed acceptance of regex as second argument of deps.
Update oauth dependency to 1.4.0
Update usage of Elixir's helpers
Remove duplicated "-pa" option in erlang runtime
Merge pull request #2 from Irio/update-dependencies

Remove deprecations on Elixir 0.10.3
Start application and its dependencies in bin/twitter.mxs
Merge pull request #3 from Irio/load-app-on-twitter-example

Start application and its dependencies in bin/twitter.mxs
Gitignore log folder
Merge pull request #4 from Irio/gitignore

Gitignore log folder
Improve naming conventions and code style

Changes in variable names was based in conventions of
http://oauth.net/core/1.0/
Store Twitter API's base url in a module attribute
Include instruction to provide PIN auth in request token's command
Simplify messages shown to user