Section 7. In determining whether a partnership exists, these rules shall apply:
(1) Except as provided by section sixteen persons who are not partners as to each other are not partners as to third persons.
(2) Joint tenancy, tenancy in common, tenancy by the entireties, joint property, common property, or part ownership does not of itself establish a partnership, whether such co-owners do or do not share any profits made by the use of the property.
(3) The sharing of gross returns does not of itself establish a partnership, whether or not the persons sharing them have a joint or common right or interest in any property from which the returns are derived.
(4) The receipt by a person of a share of the profits of a business is prima facie evidence that he is a partner in the business, but no such inference shall be drawn if such profits were received in payment:
(a) Of a debt by instalments or otherwise,
(b) As wages of an employee or rent to a landlord,
(c) As an annuity to a widow or representative of a deceased partner,
(d) As interest on a loan, though the amount of payment vary with the profits of the business,
(e) As the consideration for the sale of the good will of a business or other property by instalments or otherwise.