[FIX] Division for zero quotient with either a negative divisor or dividend

[jmalovera10]

What is done?

This PR aims to solve the issue #236. It handles the case in which either the divisor or the dividend are negative and the value is 0 and dividend < divisor which results in a division under the current currency precision. To illustrate the change, here is an example of the behavior before:

iex(3)> Money.divide(Money.new(-3, :EUR), 5) # Does not add up to -3
[
  %Money{amount: 1, currency: :EUR},
  %Money{amount: 1, currency: :EUR},
  %Money{amount: -1, currency: :EUR},
  %Money{amount: 0, currency: :EUR},
  %Money{amount: 0, currency: :EUR}
]

And the behavior after:

iex(3)> Money.divide(Money.new(-3, :EUR), 5) # Adds up to -3
[
  %Money{amount: -1, currency: :EUR},
  %Money{amount: -1, currency: :EUR},
  %Money{amount: -1, currency: :EUR},
  %Money{amount: 0, currency: :EUR},
  %Money{amount: 0, currency: :EUR}
]

Also more thorough tests are added on negative values division to ensure proper behavior.