Create Model for ExpenseLog

[zacck-zz]

An ExpenseLog is generated everytime a user spends in a MoneyLog, it contains the following details

• name: name of this expense
• log_category_id: id of the LogCategory this expense belongs to
• desc: a description of this expense
• amount: amount spent in this expense
• payment_method_id: id of PaymentMethod used for this expense
• money_log_id: id of MoneyLog this expense belongs to
• date: date of this expense

A model will be needed to

• Create an expense if name and amount spent provided
• Update expense details if id is provided

[zacck-zz]

Notes

Needs to be associated to a Payment Method #113