Custom pop-out sidebar for article pages

[joshdarby]

Changes

This pull request makes the following changes:

• Created new borderzine_shortcode_sidebar and borderzine_do_sidebar helper functions (borrowed from scaip) to allow the ability to display selected sidebars through a shortcode.
• Added basic styling for pop up created by pop up maker plugin.

Why

For #4

Testing/Questions

Features that this PR affects:

• Article pages

Questions that need to be answered before merging:

• [ ] Should we add any more "default" styles to this?

Steps to test this PR:

1. Install and activate pop up maker plugin
2. Create new pop-up and and set it to display on all posts with a slide animation to the right and position to the right
3. Add the new sidebar shortcode to the pop up content [borderzine_sidebar sidebar="your_sidebar"]
4. View a post and verify the popup works and the sidebar is displayed inside of it as expected

[benlk]

sidebar="your_sidebar"

Get a list of sidebar IDs from wp sidebar list

Should we add any more "default" styles to this?

I don't think we need to, but we should make detailed notes or exports of the Popup Theme and the Popup that you created in testing, so that they can be imported on the live site.

[joshdarby]

I don't think we need to, but we should make detailed notes or exports of the Popup Theme and the Popup that you created in testing, so that they can be imported on the live site.

@benlk I think the idea is that we're going to let the client handle configuring the Popup theme and settings to however they want it.