Fix `hasAssign` function to allow uuid keys in objects
Fix `hasAssign` function to allow uuid keys in objects

Before this change, when `uuid` key started with numbers the `parseInt`
returned a truncated value, for example

  $ parseInt('416eae54-cfb0-4245-a812-be8d307f8d1a', 10)
  > 416

However, when the key started with an alpha character `parseInt`
returned NaN

  $ parseInt('a8e9a1dc-eda6-4e32-a552-39aa054e069f', 10)
  > NaN

Using a regular expression to check first that all string positions
are digits solves the problem.

julianocomg/react-native-form