Install Moltin cart to Symfony 2

I can not get Moltin Cart plugin to install for symfony 2.7. I get following issues when I try to install.

Problem 1
  - Installation request for moltin/cart dev-master -> satisfiable by moltin/c art[dev-master].
  - moltin/cart dev-master requires moltin/tax dev-master -> no matching packa ge found.

Potential causes:
  - A typo in the package name
  - The package is not available in a stable-enough version according to your min imum-stability setting

This is my composr.lock

.....
"aliases": [],
"minimum-stability": "stable",
"stability-flags": [],
"prefer-stable": false,
"prefer-lowest": false,
"platform": {
    "php": ">=5.3.3"
},
.....

And this is my composer.json complete file

{
"name": "symfony/framework-standard-edition",
"license": "MIT",
"type": "project",
"description": "The \"Symfony Standard Edition\" distribution",
"autoload": {
    "psr-0": { "": "src/", "SymfonyStandard": "app/" }
},
"require": {
    "php": ">=5.3.3",
    "symfony/symfony": "2.5.*",
    "doctrine/orm": "~2.2,>=2.2.3,<2.5",
    "doctrine/dbal": "<2.5",
    "doctrine/doctrine-bundle": "~1.2",
    "twig/extensions": "~1.0",
    "symfony/assetic-bundle": "~2.3",
    "symfony/swiftmailer-bundle": "~2.3",
    "symfony/monolog-bundle": "~2.4",
    "sensio/distribution-bundle": "~3.0,>=3.0.12",
    "sensio/framework-extra-bundle": "~3.0,>=3.0.2",
    "incenteev/composer-parameter-handler": "~2.0",
    "symfony/var-dumper": "^2.7",
    "jms/serializer-bundle": "^1.0",
    "symfony/finder": "^2.7",
    "moltin/cart": "dev-master"
},
"require-dev": {
    "sensio/generator-bundle": "~2.3"
},
"scripts": {
    "post-root-package-install": [
        "SymfonyStandard\\Composer::hookRootPackageInstall"
    ],
    "post-install-cmd": [
        "Incenteev\\ParameterHandler\\ScriptHandler::buildParameters",
        "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::buildBootstrap",
        "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::clearCache",
        "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::installAssets",
        "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::installRequirementsFile",
        "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::removeSymfonyStandardFiles"
    ],
    "post-update-cmd": [
        "Incenteev\\ParameterHandler\\ScriptHandler::buildParameters",
        "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::buildBootstrap",
        "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::clearCache",
        "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::installAssets",
        "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::installRequirementsFile",
        "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::removeSymfonyStandardFiles"
    ]
},
"config": {
    "bin-dir": "bin"
},
"extra": {
    "symfony-app-dir": "app",
    "symfony-web-dir": "web",
    "incenteev-parameters": {
        "file": "app/config/parameters.yml"
    },
    "branch-alias": {
        "dev-master": "2.5-dev"
    }
}

}

This is Moltin/cart site page link. It would be great help if someone can look into it.

If you want to install a package that depends on non-stable packages, you will to explicitly require those packages too or lower the minimum stability setting in your project's Composer configuration.