Fixing reported issues:

* Injecting the ExpressionLanguage instance as an optional parameter on the ExpressionCondition class, this allows to inject a custom ParserCacheInterface implementation
* Updated composer.json
* Fixed the order of the use statements
* Added a couple more of tests to ExpressionCondition to check for the SyntaxError exception on the holdsFor method in case of malformed expressions and to test the case when the expression returns a non boolean value
* Added simple logic to default to false if the evaluated condition doesn't return bool, in this case if anything other than "true" gets returned then the condition will evaluate to false

Still we need to define what to do when a SyntaxError on the holdsFor method gets thrown, which effectively will break the flow.