Updating BinaryFile model function 'get_MD5' to use just lower case to save confusion.

Signed-off-by: Rob Dobson <rob@rdobson.co.uk>
Updating tests to specify the lower case 'get_md5' function.

Signed-off-by: Rob Dobson <rob@rdobson.co.uk>
Merge pull request #1 from rdobson/fix_get_md5

Fix call for getting a md5 for a binary. Use lower case to save confusion.