sudo: create module, remove old files

For the sake of structuring our puppet classes/manifests according to
the "standard" structure expected by puppet.

Also:
- removed the sudo::appserver class, that was used in role::snapshot::common
  and nowhere else.

Change-Id: Ic7e883f85b81b516b424168be2a3380dcc5f3121
Signed-off-by: Giuseppe Lavagetto <glavagetto@wikimedia.org>