more preloader porting to Rails 4
use new activerecord api
add the original exception's backtrace when raising

just raising an exception with the string will lose the backtrace of the
original exception.  This patch adds the backtrace from the original
exception so we can tell where the real error originates.
remove partial updates on serialized column support

this was fixed in 4.2, so we don't need this anymore
more old AR syntax => new AR syntax
old AR => new AR
decompose options passed to this method and convert to new AR

we should push these calls upstream, but we'll add some nasty code right
now to support the current API.
old AR => new AR
fix habtm join table name

habtm join table is based off the `table_name` so it doesn't intuit the
table name in our case.
old AR => new AR
just call the method rather than sending
SCVMM - DB error VM with multiple VHDs on volume

Make sure the VM's storages hash does not contain duplicates.

https://bugzilla.redhat.com/show_bug.cgi?id=1173251
Merge branch 'master' into rails4

* master:
  SCVMM - DB error VM with multiple VHDs on volume
  just call the method rather than sending