Don't worry about long Lines

This makes the command look ridiculous once it's actually run through
Fabric, so I'm just going to ignore the PEP8 style for now.
Wrapping import in conditional error messages

We have a bootstrap function that should get all the required
submodules, but that's not too much use if the fab recipes always error
out before you ever get them. So I'm wrapping the import of the
submodules in a try: and putting up an error warning, to encourage
people to get the submodules by running the `fab bootstrap` command.