Add ref

[oknemi]

This is intended to custom focus on input element by ref.

[coveralls]

Coverage remained the same at 98.936% when pulling f09d799 on oknemi:add-ref into 4b085f4 on charliekassel:master.

[charliekassel]

Not sure why this is needed as a prop @oknemi?
ref can be added when adding the component to the DOM.

<datepicker ref="mypicker"/>

[oknemi]

Hi, @charliekassel. I want to make it clear, that for me it is useful when calendar shows on focus. I hope #210 will be merged one day.

It can be useful when you need to focus on input. It doesn't work if I add ref attribute directly to the component, as you suggested. Because there's no focus function. So, in such case, I need to go throw all children elements and find input element.

[coveralls]

Coverage remained the same at 99.02% when pulling a16a069 on oknemi:add-ref into 0db6f1e on charliekassel:master.

[Eduruiz]

@oknemi did you manage to make datepicker open on focus? If so, can you explain how? I'm struggling with this task.

[oknemi]

@Eduruiz I made separate input and datepicker with inline="true". Then I made my custom wrapper for input and datepicker calendar, like dropdown. So then you can open(toggle) your dropdown with calendar by event on your custom input.

[Eduruiz]

@oknemi thanks!! I'll try it next time I run into this. For this project, I have been forced to change my datepicker component. "/