Add toQueryString and toQueryParams methods.

[patriciagao]

Methods to be able to create a URL query string from a hash. Example:

_('order=1&date=today').toQueryParams(); // => {order: '1', date: 'today'}

Or create a URL query string from a hash. Example:

_({order: '1', date: 'today'}).toQueryString(); // => 'order=1&date=today'

[PATROMO]

:+1: