ops fixes for sprint 30: /mnt perms correctly (#1648) to master

Four fixes in here 

1. /mnt perms, fixes #1648 

    The fix here is to have a script that will run on machine startup to force /mnt to 1777 permissions.  The commit log shows me first trying an upstart script, which worked sometimes, but not consistently.  I can't figure out how upstart orders scripts, nor can I figure out how to make this go late in the bringup process, so I switched to a normal "init.d" style script, linked off of runlevel 2.

2. scale number of large workers with number of CPU's, fixes #1944.  Tested by deploying a large to dev:
     ```CELERYD_OPTS="-Q:class2go-default class2go-default -c:class2go-default 8 -Q:class2go-long class2go-long -c:class2go-long 2 --time-limit=21600"```

3. terminal colors, P2, fixes #1961 

4. While I was in here I installed [mosh](http://mosh.mit.edu/) to better support lossy links.

Assigning to @jrbl but if you want to pick up @jbau that'd be fine too.