Enable side-loading of has_many, through associated resources.

Fix nested links within returned objects to enable has many through relationships.

Fix href with filters for has_many, :through resources

Fix spelling mistake.

Update has_many, through ids in links to be strings instad of numbers

Update spec
Merge pull request #80 from thesteady/enable_has_many_through_side_loading

Enable side-loading of has_many, through associated resources.