Bundle unpacking timeout/error handling

[oceanc80]

We have this BZ open against OLM v0.1. Given we're not going to fix this bug in OLM v0.1, we should think about how we want to handle bundle unpacking taking a while.
Some initial thoughts:

• timeouts (OLM v0.1 currently has this, but the 10m timeout is getting hit)
• configurable timeouts? disabled timeouts (for case where someone doesn't care if it it takes forever to unpack the bundle)?
• some sort of backoff/retry logic