Patches for RFS Bitmap

[Chris Johns]

Hi,

This is an updated version of the patches posted by Fan Deng:

 https://lists.rtems.org/pipermail/devel/2017-October/019155.html
 https://lists.rtems.org/pipermail/devel/2017-October/019156.html
 https://lists.rtems.org/pipermail/devel/2017-October/019157.html
 https://lists.rtems.org/pipermail/devel/2017-October/019158.html

I have cleaned up the patches, fixed any errors and added some tests.

I confirmed the test failed before the patches and passed after being
applied.

Chris