add a strategy for applying conditions to MiqQueue

This commit accomplishes 2 things:

1. Removes sanitize_sql_for_conditions
2. Updates finder syntax to work with Rails 4

sanitize_sql_for_conditions is deprecated, so we need to stop using it.
This commit introduces a lambda as a strategy for applying where
conditions to the query.  This lets us keep the hash conditionals, but
optionally apply a "yaml conditional" as a string.  Since we can call
`where` twice, there is no need for sanitize_sql_for_conditions.
You're right!  I'll simplify it.