fix path option on belongs_to association

[zacharywelch]

fixes #506

path option was being ignored on belongs_to associations and replaced with the default. According to the documentation

Options Hash (opts):
:path (Path) — The relative path where to fetch the data (defaults to /class_name.pluralize/id)

Example of the behavior

class User
  include Her::Model
  
  belongs_to :company, path: "/organizations/:id", 
                       foreign_key: :organization_id, 
                       data_key: :organization
end


class Company
  include Her::Model
end

Before

> user = User.find(1) 
# GET "/users/1", response is:
# {
#   "id": 1,
#   "name": "George Michael Bluth",
#   "organization_id": 2
# }

> user.company # goes to wrong path
# GET "/companies/2"

After

> user = User.find(1) 
# GET "/users/1", response is:
# {
#   "id": 1,
#   "name": "George Michael Bluth",
#   "organization_id": 2
# }

> user.company # goes to correct path
# GET "/organizations/2"

[edtjones]

Thanks as ever for being a hero @zacharywelch 👍

[seanbjornsson]

Thanks for the fix @zacharywelch !