Add json export of recipe

[vsoch]

Should work like:

spython parse --json Dockerfile

[vsoch]

This was done with #119

$ spython recipe ../sregistry-cli/Dockerfile --json
{
    "entrypoint": [
        "sregistry"
    ],
    "files": [
        [
            ".",
            "/code"
        ]
    ],
    "install": [
        "\n",
        "#########################################\n",
        "# Singularity Registry Global Client\n",
        "# \n",
        "# docker build -t vanessa/sregistry-cli .\n",
        "# docker run vanessa/sregistry-cli\n",
        "#########################################\n",
        "\n",
        "\n",
        "apt-get update && apt-get install -y git build-essential \\",
        "libtool \\",
        "squashfs-tools \\",
        "libarchive-dev \\",
        "autotools-dev \\",
        "automake \\",
        "autoconf \\",
        "uuid-dev \\",
        "libssl-dev",
        "\n",
        "/opt/conda/bin/pip install dateutils",
        "\n",
        "# Install Singularity\n",
        "cd /opt",
        "git clone -b vault/release-2.6 https://www.github.com/sylabs/singularity.git",
        "cd singularity",
        "./autogen.sh && ./configure --prefix=/usr/local && make && make install",
        "\n",
        "mkdir /code",
        "/opt/conda/bin/pip install setuptools",
        "/opt/conda/bin/pip install scif",
        "\n",
        "scif install /code/sregistry-cli.scif",
        "\n",
        "cd /code",
        "test -f /usr/bin/python || ln -s /opt/conda/bin/python /usr/bin/python",
        "\n",
        "/opt/conda/bin/pip install -e .[all]"
    ],
    "labels": [
        [
            "maintainer vsochat@stanford.edu"
        ]
    ],
    "workdir": "/code"
}