NPE in check lifecycle rule configuration

[jayeshbhardwaj]

Currently We get an NPE if the lifecycle rule has no prefix added to its scope (i.e if it applies to the whole bucket)

java.lang.NullPointerException
at java.lang.String.startsWith(String.java:1405)
at java.lang.String.startsWith(String.java:1434)
at com.databricks.spark.redshift.Utils$$anonfun$5.apply(Utils.scala:140)
at com.databricks.spark.redshift.Utils$$anonfun$5.apply(Utils.scala:136)
at scala.collection.Iterator$class.exists(Iterator.scala:919)
at scala.collection.AbstractIterator.exists(Iterator.scala:1336)
at scala.collection.IterableLike$class.exists(IterableLike.scala:77)
at scala.collection.AbstractIterable.exists(Iterable.scala:54)
at ....

[markdessain]

Seems to be the same as: #346