remove automatic inclusion of BelongsToHstore::Association in ActiveRecord::Base
you must now include the association in the base class that contains the hstore.
this reduces the overhead of read_attribute/write_attribute on AR classes that do not involve hstore associations.
use a class attribute to store valid attribute names for faster lookup
this approach initializes the attribute array at class definition time and reduces parent class lookups
Merge pull request #1 from universitynow/feature/performance_tuning

Improve performance of read_attribute