Check for fmuexport binary

Closes NTNU-IHB#129

Author: jschueller

pythonfmu/__init__.py

@@ -4,3 +4,6 @@
 from .fmi2slave import Fmi2Slave
 from .variables import Boolean, Integer, Real, String
 from .default_experiment import DefaultExperiment
+
+if not FmuBuilder.has_binary():
+    raise ValueError("FmuBuilder binary is missing")