dependency versions

[bart3r]

When installing this gem, I get the error:

Bundler could not find compatible versions for gem "hashie":
  In snapshot (Gemfile.lock):
    hashie (= 3.5.7)

  In Gemfile:
    hashie

    omniauth was resolved to 1.8.1, which depends on
      hashie (< 3.6.0, >= 3.4.6)

    simplemdm was resolved to 1.3.0, which depends on
      hashie (~> 3.4.4)

I noticed in your gemspec file, you specify:
spec.add_dependency "hashie", "~> 3.4.4"

This will exclude newer versions of hashie, e.g >= 3.5

Why are you restricting this for both hashie and rest-client gems? It will cause many people problems.