Subtransformation from jar file bug

comment from file:
```
// This is only called for files which do not exist in the Zip file
```
No, it's wrong. After garbage collector evicts Soft/Weak references from ReferenceQueue from cache, and JobEntryTrans asks those file again, it will couse a bug at ZipFileObject.java:159. (new FileSystemException("vfs.provider/read-not-file.error", getName()))
Here stack trace of such situation:
```
    org.apache.commons.vfs.provider.zip.ZipFileSystem.createFile(ZipFileSystem.java:172)
    org.apache.commons.vfs.provider.AbstractFileSystem.resolveFile(AbstractFileSystem.java:344)
    org.apache.commons.vfs.provider.AbstractFileSystem.resolveFile(AbstractFileSystem.java:315)
    org.apache.commons.vfs.provider.AbstractFileSystem.getRoot(AbstractFileSystem.java:284)
    org.apache.commons.vfs.provider.AbstractLayeredFileProvider.createFileSystem(AbstractLayeredFileProvider.java:93)
    org.apache.commons.vfs.provider.AbstractLayeredFileProvider.findFile(AbstractLayeredFileProvider.java:65)
    org.apache.commons.vfs.impl.DefaultFileSystemManager.resolveFile(DefaultFileSystemManager.java:693)
    org.apache.commons.vfs.impl.DefaultFileSystemManager.resolveFile(DefaultFileSystemManager.java:621)
    org.pentaho.di.core.vfs.KettleVFS.getFileObject(KettleVFS.java:153)
    org.pentaho.di.core.vfs.KettleVFS.getFileObject(KettleVFS.java:104)
    org.pentaho.di.trans.TransMeta.<init>(TransMeta.java:2760)
    org.pentaho.di.trans.TransMeta.<init>(TransMeta.java:2741)
    org.pentaho.di.job.entries.trans.JobEntryTrans.getTransMeta(JobEntryTrans.java:1158)
    org.pentaho.di.job.entries.trans.JobEntryTrans.execute(JobEntryTrans.java:621)
    org.pentaho.di.job.Job.execute(Job.java:589)
    org.pentaho.di.job.Job.access$000(Job.java:103)
    org.pentaho.di.job.Job$1.run(Job.java:703)
    java.lang.Thread.run(Thread.java:662)
```
Those pull request fixes that problem.