This component's job is to map prefixes to filenames and
increment the sequence number of a file when appropriate.
It also will list files associated with a prefix.
* Generate a list of write intervals at test start
* Add a rewrite command to validate writes cannot be
overwritten
* Fixed a bug when validating offsets after appends
* Test model under parallel execution
Previously if a lookup of an offset and size tuple
from the process dictionary returned a checksum that
was different from the one we were expecting, it
would trigger a case clause exception. We should
handle that case a little more elegantly.
