'Resolver install dependency should return True when installation succeeds,
False if not successful'

def _install_dependency(self, index, **payload):

    resolver = self._dependency_resolver(index)
    if (not hasattr(resolver, 'install_dependency')):
        raise NotImplemented()
    (name, version, type, extra_kwds) = self._parse_dependency_info(payload)
    return resolver.install_dependency(name=name, version=version, type=type, **extra_kwds)
