LIVY-361. If LIVY_PID_DIR contains space, stop livy-server failed
LIVY-361. If LIVY_PID_DIR contains space, stop livy-server failed

[https://issues.cloudera.org/browse/LIVY-361](https://issues.cloudera.org/browse/LIVY-361)
There is an error in cheking pid file existence while stop livy-server. If LIVY_PID_DIR contains space, It is unable to get the pid file within it, so stop livy-server failed.

Author: davidxdh <xu.donghui@zte.com.cn>

Closes #8 from davidxdh/dev361.

meisam/incubator-livy,ajbozarth/incubator-livy,meisam/incubator-livy,meisam/incubator-livy,meisam/incubator-livy,ajbozarth/incubator-livy,ajbozarth/incubator-livy,meisam/incubator-livy,ajbozarth/incubator-livy,meisam/incubator-livy,ajbozarth/incubator-livy,ajbozarth/incubator-livy