Omit date selection field for non time based searches

[quintanilhar]

Hello guys!

It will omit the date select field for non-time based searches.

The HTTP Search (non-time based) will look like this:

The ECL Search will look like as before:

This PR's closes #114.

[kiwiz]

Thanks for the PR! Some additional work needs to be done for Searches that support multiple sources. The Elasticsearch_Search is a good example: It has a isTimeBased method that gives this information.

I think we'll need the following:

• Pass a mapping of [sources -> whether it's time based] to the front end via REST_Data.
• Look up the key whenever the source type changes and show/hide the buttons.

Lemme know if you'd like to take a stab at this. I'm also happy to merge this and finish up.