Fix IllegalAccessError in MrContext when running in local mode

[WARN] LocalJobRunner - job_local1120324947_0001 <java.lang.Exception: java.lang.IllegalAccessError: tried to access class org.apache.hadoop.mapreduce.lib.input.TaggedInputSplit from class org.apache.hadoop.mapreduce.lib.input.ProxiedInpu
tSplit$>java.lang.Exception: java.lang.IllegalAccessError: tried to access class org.apache.hadoop.mapreduce.lib.input.TaggedInputSplit from class org.apache.hadoop.mapreduce.lib.input.ProxiedInputSplit$
        at org.apache.hadoop.mapred.LocalJobRunner$Job.runTasks(LocalJobRunner.java:462)
        at org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:522)
Caused by: java.lang.IllegalAccessError: tried to access class org.apache.hadoop.mapreduce.lib.input.TaggedInputSplit from class org.apache.hadoop.mapreduce.lib.input.ProxiedInputSplit$
        at org.apache.hadoop.mapreduce.lib.input.ProxiedInputSplit$.fromInputSplit(ProxyTaggedInputSplit.scala:24)
        at com.ambiata.ivory.mr.MrContext$.getSplitPath(Context.scala:62)
        at com.ambiata.ivory.ingest.IngestMapper.setup(mr.scala:206)
        at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:142)
Merge pull request #97 from ambiata/cofarrell/mr-split-reflect

Fix IllegalAccessError in MrContext when running in local mode