upgrade-charm hook

[James Beedy]

How do people feel about splitting the upgrade-charm hook into multiple hooks to facilitate better resource management?

What I'm thinking would be super helpful would be to have the upgrade-charm hook still active for charm upgrades, and have separate hooks or flags that would indicate resource upgrades. 

I'm thinking something like:

'juju attach myapp myresource=myresource.file'

Would cause the 'upgrade-resource-myresource'  hook to become active on instances of 'myapp'.

I feel that having this affinity from resource -> resource-upgrade-<resource-name> hook would be a huge win for resource management.

Thoughts?