Merge branch 'issue_80' into financial
issue_85: Category model
issue_85: replace ExpType with ExpenseCategory, manage Categories
issue_85: record type of Category
issue_85: fix link to edit category on index
Merge branch 'issue_85' into financial
issue_81: add, edit, update income
issue_81: use IncomeCategory
issue_81: add income to navigation
issue_81: fix missing income resource
issue_81: add action for income
issue_81: fix saving income and redirect