RFC on Cloud Images: Make /tmp a tmpfs

[Serge Hallyn]

Quoting Ben Howard (ben.howard at canonical.com):
> All,
> 
> On the Ubuntu Cloud Images, we have a request to make /tmp a tmpfs. The
> rationale, from the bug:
>  * Performance - much faster read/write access to data in /tmp
>  * Security - sensitive data would be cleared from memory on boot,
>    rather than written (leaked) to disk -- important for encryption
>    scenarios

I generally prefer that as well

I wondered why were weren't doing that by default.