Update fetchUtils.py

Added a test to fetch_remote_files to check for any existing temporary files present in the directory, and not download them if they are there and contain at least 1MB of data.
Update fetchUtils.py

Improved file size check
Update fetchUtils.py

Added casting to size check to ensure validity on all platforms
Update fetchUtils.py

Fixed typo
Merge pull request #95 from aburrell/develop

Update fetchUtils.py

Looks good to me. Thanks for the update here!  Hopefully this will reduce the amount of file downloading that will occur.