Set the configuration to the real input split instantiated in DeprecatedInputFormatWrapper

Greetings,

please, consider pulling this modifications.

Updated `DeprecatedInputFormatWrapper#getSplits(JobConf, int)` to instantiate `InputSplitWrapper` passing the JobConf configuration.
Updated `InputSplitWrapper` to be configurable.

This changes will allow the real input split to get the configuration from the front when instantiated.

Recently I have started to test Cascading in local and cluster mode and I have been trying to launch flows conveying the configuration files in the .jar (core-site.xml, mapred-site.xml, hbase-site.xml, etc...) and not conveying the configuration files (configuration set in code).

I found that my InputSplits were not receiving the configuration from the front, because `DeprecatedInputFormatWrapper$InputSplitWrapper` was filtering it. The solution shown here is define the InputSplitWrapper as Configurable (we don't lose anything ;) and set the configuration at instantiation time.

I need this to create a GoraTap for Cascading.
Bugs related: https://github.com/cwensel/cascading/pull/29