Add package mappings for MySQL-MariaDB

Partial-Bug: #1213891

Change-Id: I1ac1d11ff1716eccee4c734395282be25dd5b541
Add option --min-tmpfs <size> to disk-image-create

In some scenarios, the required space in the tmpfs partition can be
larger (or smaller) than the default one, producing errors due to
the lack of enough space (or performance penalties for not using
tmpfs).

Using --min-tmpfs <size>, we can hint the working set size we'll need
and let dib choose to avoid or use tmpfs.

Change-Id: I7d5fe498302a100c8555ae542268e14b21f3a0c5
Merge "Add package mappings for MySQL-MariaDB"
Merge "Add option --min-tmpfs <size> to disk-image-create"