Date column are not commited by the datasource (and solution)

Hello,

Your implementation of deepextend doesn't work with Date, Buffer and RegEx.
This cause all editor based on datepicker which use the Date type as backend, to not be able to commit the edited value into the datasource.

Here is your code : https://github.com/akveo/ng2-smart-table/blob/master/src/ng2-smart-table/lib/helpers.ts
Here is the bug report (fixed in 2014) in the deepextend project : https://github.com/unclechu/node-deep-extend/issues/8
And the latest version : https://github.com/unclechu/node-deep-extend/blob/master/lib/deep-extend.js

Thanks