call setConf from input format if it is Configurable

As I told in spark-user [thread](https://groups.google.com/forum/?fromgroups=#!topic/spark-users/t_C6wsSWD-Q) spark failed when I used [KijiTableInputFormat](https://github.com/kijiproject/kiji-mapreduce/blob/master/kiji-mapreduce/src/main/java/org/kiji/mapreduce/framework/KijiTableInputFormat.java) which implemented `Configurable` interface.
Changes in this pull request make `HadoopRDD` and `NewHadoopRDD` to detect if input format is `Configurable` and, if yes, do the `setConf`.