'Installs dependency using highest priority resolver that supports dependency installation
(Currently only the conda resolver supports this). If index is given, attempt
installation directly using the corresponding resolver.
Returns True on success, False on failure.
payload is dictionary that must container name, version and type,
e.g. {\'name\': \'numpy\', version=\'1.9.1\', type=\'package\'}'

def install_dependency(self, index=None, **payload):

    if index:
        return self._install_dependency(index, **payload)
    else:
        for index in self.installable_resolvers:
            success = self._install_dependency(index, **payload)
            if success:
                return success
        return False
