FileSystem used by prepare sections should use the configuration of the action

We should be able to propagate configurations to prepare section (delete, mkdir) of action in workflow xmls.
Though the configuration section is available per action, it is not available in for prepare tags:

A simple use-case is to support custom filesystem by configuring the filesystem impl class in configuration, but delete prepare action is not aware of configuration set in action xml.

Ex:<action name="myfirstHadoopJob">
<map-reduce>
<job-tracker>foo:9001</job-tracker>
<name-node>bar:9000</name-node>
<prepare>
<delete path="hdfs://foo:9000/usr/tucu/output-data"/>
</prepare>
<job-xml>/myfirstjob.xml</job-xml>
<configuration>
<property><name>fs.s4.impl</name><value>org.apache.grid.fs.s4fs.NativeS4FileSystem</value></property>
.....

I think this can be fixed in FileSystemsActions.java