Fix paramiko test with pytest 3.4
Fix paramiko test with pytest 3.4

The 3.4 pytest release introduced a breaking change: pytest no longer
changes log levels: the default log level is now Python's default:
WARNING. This commit ensures the test no longer depends on external log
levels.

andrewsomething/libcloud,mistio/libcloud,ByteInternet/libcloud,StackPointCloud/libcloud,pquentin/libcloud,Kami/libcloud,Scalr/libcloud,pquentin/libcloud,pquentin/libcloud,ByteInternet/libcloud,mistio/libcloud,vongazman/libcloud,vongazman/libcloud,ByteInternet/libcloud,StackPointCloud/libcloud,Scalr/libcloud,andrewsomething/libcloud,apache/libcloud,Kami/libcloud,apache/libcloud,andrewsomething/libcloud,StackPointCloud/libcloud,Scalr/libcloud,mistio/libcloud,apache/libcloud,vongazman/libcloud,Kami/libcloud