Serverless-offline: Support new runtime nodejs6.10 of the last serverless and lambda versions

[joseSantacruz]

Please can you update the plugin to support the new runtime nodejs6.10, I just made the change on the index.js

if (['nodejs', 'nodejs4.3', 'babel', 'nodejs6.10'].indexOf(serviceRuntime) === -1) {
      this.printBlankLine();
      this.serverlessLog(`Warning: found unsupported runtime '${serviceRuntime}'`);
      return;
    }

[lteacher]

This was added in #221. Also a duplicate PR was closed for the same change so you need to check your version.

[dherault]

npm update serverless-offline should fix it.