Add better error message for unknown language

Exception in thread "main" org.sonar.batch.bootstrapper.BootstrapException: java
.lang.RuntimeException: Quality profile not found for symfony:symfony, language
php
        at org.sonar.runner.Runner.delegateExecution(Runner.java:189)
        at org.sonar.runner.Runner.execute(Runner.java:78)
        at org.sonar.runner.Main.main(Main.java:61)
Caused by: java.lang.RuntimeException: Quality profile not found for symfony:sym
fony, language php
        at org.sonar.batch.DefaultProfileLoader.load(DefaultProfileLoader.java:4
4)
        at org.sonar.batch.ProfileProvider.provide(ProfileProvider.java:36)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
        at java.lang.reflect.Method.invoke(Unknown Source)
        at org.picocontainer.injectors.MethodInjector.invokeMethod(MethodInjecto
r.java:142)
        at org.picocontainer.injectors.MethodInjector.access$000(MethodInjector.
java:38)
        at org.picocontainer.injectors.MethodInjector$2.run(MethodInjector.java:
126)