make it possible to _not_ declare required tasks

subclasses shouldn't care necessarily about the abstract class'
depenencies - just ensure they are available and move along
Merge release/v1.3.1 into develop
account for there being no js config
Merge pull request #14 from nodesagency/feature/gearman-tasks

make it possible to _not_ declare required tasks
Preparing release
Preparing submodules for release
Updating semver
Finish release
merge release/v1.3.2 into master