Missing double quote causes server not to start

[edwardcapriolo]

What changes were proposed in this pull request?

bin/livy-server doesnt work at all.

How was this patch tested?

edward@fedora:~/incubator-livy$ bin/livy-server 
WARNING: Unknown module: ALL_UNNAMED specified to --add-exports
log4j:WARN No appenders could be found for logger (org.apache.livy.server.AccessManager).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
Exception in thread "main" java.lang.IllegalArgumentException: Livy requires the SPARK_HOME environment variable
	at org.apache.livy.utils.LivySparkUtils$$anonfun$1.apply(LivySparkUtils.scala:55)
	at org.apache.livy.utils.LivySparkUtils$$anonfun$1.apply(LivySparkUtils.scala:55)
	at scala.Option.getOrElse(Option.scala:121)
	at org.apache.livy.utils.LivySparkUtils$.testSparkHome(LivySparkUtils.scala:54)
	at org.apache.livy.server.LivyServer.start(LivyServer.scala:79)
	at org.apache.livy.server.LivyServer$.main(LivyServer.scala:439)
	at org.apache.livy.server.LivyServer.main(LivyServer.scala)
edward@fedora:~/incubator-livy$ git status

Please review https://livy.incubator.apache.org/community/ before opening a pull request.

[edwardcapriolo]

https://issues.apache.org/jira/browse/LIVY-1023

[gyogal]

LGTM, thank you for fixing this!