Make it work by default

_defaults needs an object. When you don't specify a behat section using "initConfig" in your gruntfile it will fail:

Registering "grunt-parallel-behat" local Npm module tasks.
Reading /home/develop/Dokumente/workspace/topconew/node_modules/grunt-parallel-behat/package.json...OK
Parsing /home/develop/Dokumente/workspace/topconew/node_modules/grunt-parallel-behat/package.json...OK
Loading "parallel-behat.js" tasks...ERROR
>> TypeError: Cannot read property 'src' of undefined
>>     at /home/develop/Dokumente/workspace/topconew/node_modules/grunt-parallel-behat/node_modules/underscore/underscore.js:803:18
>>     at Array.forEach (native)
>>     at .each..forEach (/home/develop/Dokumente/workspace/topconew/node_modules/grunt-parallel-behat/node_modules/underscore/underscore.js:78:11)
>>     at Function._.defaults (/home/develop/Dokumente/workspace/topconew/node_modules/grunt-parallel-behat/node_modules/underscore/underscore.js:800:5)