BREAKAGE: configuration's password, salt and sub_funcs now are under session_params

[peppelinux]

With this PR we have this new configuration parameter called "session_params" that contains all the paramenters involved in session management configuration.

  "session_params": {
      "password": "__password_used_to_encrypt_access_token_sid_value",
      "salt": "salt involved in session sub hash ",
      "sub_func": {
        "public": {
          "class": "oidcop.session.manager.PublicID",
          "kwargs": {
            "salt": "sdfsdfdsf"
          }
        },
        "pairwise": {
          "class": "oidcop.session.manager.PairWiseID",
          "kwargs": {
            "salt": "sdfsdfsdf"
          }
        }
     }
  },

this PR fixes #60
@rohe I know that's something for 2.1.0 release but believe me, I couldn't resist, it was very easy to be implemented :)