Make Role explicitly hashable.

[bonjourmauko]

Technical changes

• Make Role hashable
• Details:
  • By introducing __eq__, naturally Role became unhashable, because equality was calculated based on a property of Role (role.key == another_role.key), and no longer structurally ("1" == "1").
  • This changeset removes __eq__, as Role is being used downstream as a hasheable object, and adds a test to ensure Role's hasheability

[coveralls]

coverage: 74.114% (+0.008%) from 74.106% when pulling df283ed038c6411a72680c48f9d01d4449664a1d on make-role-hashable into 8994f8c6a30a60fd7c63071fb8e50a5dcff85a6c on master.

[benjello]

@maukoquiroga : I let you merge after rebase if needed.

[bonjourmauko]

Thanks @benjello