The original commit adding support for process limits only wired
up address space, max files and resident set size limits. This
is not sufficient to enable nova to protect qemu-img commands
against malicious images.
This commit adds support for the remaining limits supported
by python: core file size, cpu time, data size, file size,
locked memory size, max processes and stack size.
Related-bug: #1449062
Change-Id: I164c4b35e1357a0f80ed7fe00a7ae8f49df92e31
8af826953d