Remove unnecessary whitespace
Add stock Ubuntu common-session-noninteractive

Adds the stock configuration for the common-session-noninteractive
file from Ubuntu Precise's libpam-runtime package.

Added in full to provide a reference point for changes against future
Ubuntu versions.
Amend common-session-noninteractive stock config

Modifies common-session-noninteractive to match GOV.UK's common-session.
[#62625164] Enforce limits.conf using pam_limits

Enforces the limits set in /etc/security/limits.conf by including
pam_limits.so in common-session and common-session-noninteractive.

Tested on Precise and Lucid:

```
root@vm:~# sudo -u deploy bash -c 'ulimit -n; ulimit -u'
16384
512
```
Merge pull request #2 from alphagov/62625164-enforce-pam-limits

Enforce ulimits