bump excon dep
v1.23.0
add hash type attribute
Revert "add hash type attribute"

This reverts commit cc43267abf749c32746512841c86c2e62ddc308d.
update contributors
Checking for nil value as default option instead of false.
It was checking for false which makes impossible to have an attribute
with default value equal false.
Added regression test.
Merge pull request #57 from zertico/fix_default_value

Checking for nil value as default option instead of false.
Fixed default value on a new object with a custom value

It was always returning the default value when not persisted.
Merge pull request #58 from zertico/fix_default_value

Fixed default value on a new object with a custom value