Conversation history option

Hi, this is my first message on GitHub, please, excuse me if I'm doing something wrong.

First I want to thank you your excellent work with Conversations. You are doing it right, but I wish Conversations had an optional 'save history' option. I want to save with me all my conversations, but I saw that in Conversations the messages get autoremoved.

Sorry for the example, but this is actually a good feature that Whatsapp uses and I liked to enjoy it on Conversations.

Would be so nice that we could select an external microSD folder to save them, would be really cool to synch it with my Owncloud account or similar to have all my messages with me.

Again, thank you for your time and see you!