Code was not adding foreign_type constraint

When we already had some constraints on the relation definition.

Ex, below case did not work:
  has_many :constraints, as: :restricted_object, integer_type: true,
           :conditions => { :is_deleted => false }

A workaround prior to this commit was to use the reverse mapping:
  has_many :constraints, as: :restricted_object, integer_type: true,
           :conditions => { :is_deleted => false, restricted_object_type: RESTRICTED_OBJECT_MAP_REVERSE[self.to_s] }
Merge pull request #5 from tispratik/master

Code was not adding foreign_type constraint
Version Bump
Have the foreign_type use the base class to deal with STI classes properly
VERSION BUMP
If we assign nil to the association, we should not fail
Check the subclass first before checking the base_class of the sti
Merge branch 'master' into rails-4

Conflicts:
	lib/polymorphic_integer_type/extensions.rb