don't need to handle Groovy in SnakeYaml any more as all the relevant classes are written in Java
#59 tinkering
#59 dumb proof of concept implementation
#59 write body to correct root directory
#59 writes the body out to tmpdir rather than tape root
#59 refactor loader<->tape relationship so tape doesn't need unreasonable amount of context
#59 almost working

now writes to correct directory. Need to make filenames unique (indexed?)
incorrect scope on method
#59 better separation of responsibilities around where files are kept
#59 refactored so much out of StorableTape there's no need for it any more
#59 extract MIME->file extension code out to utility class
#59 clean up some unnecessary code
#59 write file path to YAML relative to tape root
#59 read files in as well
fix ordering of top level properties in YAML

was only sorting if for `Tape` class not any implementation of it
#59 failing test for remaining functionality

need a good strategy for consistently naming the body files