Improvement to develop behaviors

This is an improvement for behavior devs. When developing a behavior, there is no composer.lock file containing the information about the behavior, instead these information are stored in the composer.json file. This PR also searches in the composer.json. This is extremly handy when writing tests, which involves running a propel build. These builds so far can't find the behavior which is currently worked on. This is fixed with this PR. Tests included.