Vault secret resolver module

[vixns]

Add a new module to resolve secrets from hashicorp vault.
This module is compatible with approle (recommended) and token methods.

Sample configuration

{
    "libraries": [
        {
            "file": "/usr/lib/mesos/modules/libvaultsecretsresolver.so",
            "modules": [
                {
                    "name": "org_apache_mesos_VaultSecretsResolver",
                    "parameters": [
                        {
                            "key": "vault_addr",
                            "value": "https://REDACTED:8200"
                        },
                        {
                            "key": "vault_role_id",
                            "value": "REDACTED"
                        },
                        {
                            "key": "vault_role_secret",
                            "value": "REDACTED"
                        },
                        {
                            "key": "vault_cacert",
                            "value": "/etc/ca.pem"
                        }
                    ]
                }
            ]
        }
    ]
}