Feature: Add t5_base Summarization agent abilities

[bgoober]

In this pull request I have:

• Added new SummarizationRequest and SummarizationResponse classes
• Added a new message handler for summarization requests to the base agent
• Split the client agents into distinct translation and summarization processes
• Created a new summarization_client.py agent for the agent bureau
• Renamed the previous client agent to translation_client.py
• Updated the README with new instructions and future modifications/considerations

Users can now choose to run either the translation client or the summarization client, depending on which process they would like to use from the t5_base model. The agents now accept their own inputs and make their own distinct requests.