Configurable System Prompt

[iwr-redmond]

It would be helpful to be able to configure the System Prompt. This can be done by adding the system parameter.

[chyok]

Good idea. Ollama has recently updated many APIs, and the 'system' parameter, which couldn't be set before, is now available. However, I'm quite busy with work at the moment, so I'll update it when I have some free time. It would be even better if someone could help by submitting a pull request.