ENH: decrease default cache size
ENH: decrease default cache size

As discussed @ EuroScipy.

aabadie/joblib,lesteve/joblib,lesteve/joblib,karandesai-96/joblib,joblib/joblib,tomMoral/joblib,joblib/joblib,karandesai-96/joblib,aabadie/joblib,tomMoral/joblib