Support array of non-database backed attrs for meta data

The previous implementation only pulled the attribute from the invoking
model if there was one attribute (:meta => :foo)

This changes allow specifying an array of attributes that aren't
database backed.  (:meta => [:foo, :bar])
Version bump to 1.2.3.sermo
Merge pull request #2 from ajvargo/support_array_of_non_db_attrs_for_metadata

Support array of non db attrs for metadata