adding ability to do conditional searches…

via hierarchically ordered processor hashes

In the following configuration, 
if `params[:team_id]` is present and
if `params[:is_manager]` is present and truthy
or `params[is_owner]` is present and truthy
the search method called on `MemberMapper` will be `#find_managers_by_team_id` or `#find_owners_by_team_id` instead of `#find_by_team_id`

The managers scope will be given preference over the owners scope due to it’s appearance first in the processors array

```ruby
  include Pygmy.search(MemberMapper, :search_conditions => [
    :id, :user_id,
    {:for => :team_id, :processors => [
      {:if => :is_manager, :scope => :managers},
      {:if => :is_owner, :scope => :owners}
    ]}
  ])
```
I am not sure how I feel about the type-checking here. Is there a way that we could use conversion to get everything the same? like convert the string to a hash so that we only have to type check one time?