added stub for decorator that converts message parameters
implemented tests
added test
added required dependency to system under test
fixed test: the correct values are expected
implemented parameter converter
removed parameter conversion from IntlFormatter
integrated new decorator into service definition
added test case for IntlFormatter
added tests
added additional check to avoid exceptions in case of an empty message string
added test
Merge branch 'named_to_positional_parameters_formatter'

Conflicts:
	Resources/config/services.yml
	Tests/Translator/FormatterDecoratorTest.php
	Translator/Formatting/IntlFormatter.php
changed service prefixes to improve readability