Your requirements could not be resolved to an installable set of packages.
 Problem 1
   - The requested package ezsystems/behatbundle == 6.1.0.0 could not be found.
 Problem 2
   - doctrine/cache v1.6.0 requires php ~5.5|~7.0 -> your PHP version (5.6.14-0+deb8u1) or value of "config.platform.php" in composer.json does not satisfy that requirement.
   - doctrine/cache v1.6.0 requires php ~5.5|~7.0 -> your PHP version (5.6.14-0+deb8u1) or value of "config.platform.php" in composer.json does not satisfy that requirement.
   - Installation request for doctrine/cache == 1.6.0.0 -> satisfiable by doctrine/cache[v1.6.0].

Potential causes:
- A typo in the package name
- The package is not available in a stable-enough version according to your minimum-stability setting
 see <https://getcomposer.org/doc/04-schema.md#minimum-stability> for more details.