Also, require the -as flag to be set when importing a model. This
prevents the confusing error message "invalid name".
Also, allow short names to be used when importing a model and
auto-complete the name with the default mask.
This commit copies (without history) the bmizerany/ollama-go repository
with the intention of integrating it into the ollama as a replacement
for the pushing, and pulling of models, and management of the cache they
are pushed and pulled from.
New homes for these packages will be determined as they are integrated
and we have a better understanding of proper package boundaries.