Dependency versions too old

[alexandremcosta]

{:httpoison, "~> 0.13.0"},

This forces everyone with an updated codebase to use override: true

{:httpoison, "~> 1.5", override: true}

I know it's hard to keep the lib updated, but at least make the dependencies more open for updates

[zpeters]

#45 A few other were out of date. Updated everything and made sure tests passed

[everettvody]

Is this being updated?