JsonLoader() is not working properly for maps

The code that is loading map values is ignoring the load specification and always creating String objects.

You can reproduce the bug with the following steps:

input file:
a#1

script:
A = load 'input' as (a:map[int]);
B = store A into 'output' using JsonStorage();
C = load 'output' using JsonLoader() as (a:map[int]);
D = foreach C generate a+1;

you get the following error:
java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Number
at org.apache.pig.backend.hadoop.executionengine.physicalLayer.expressionOperators.Add.genericGetNext(Add.java:89)
at org.apache.pig.backend.hadoop.executionengine.physicalLayer.expressionOperators.Add.getNext(Add.java:114)
at org.apache.pig.backend.hadoop.executionengine.physicalLayer.PhysicalOperator.getNext(PhysicalOperator.java:346)
at org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POForEach.processPlan(POForEach.java:372)
at org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POForEach.getNext(POForEach.java:297)
at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigGenericMapBase.runPipeline(PigGenericMapBase.java:283)
at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigGenericMapBase.map(PigGenericMapBase.java:278)
at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigGenericMapBase.map(PigGenericMapBase.java:64)
at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:144)
at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:764)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:370)
at org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:214)