Make Wufoo safe for https usage and async

[marekhrabe]

Summary:
This removes the ssl argument of shortcode and replaces everything to work over https. SSL used to be a paid feature over at Wufoo but that changed 5 years ago https://www.wufoo.com/blog/making-wufoo-more-secure-https/

It also turns the old embed codes into their new async version and makes sure only a single form.js would be loaded even for multiple forms.

Testing instructions: Test with various wufoo embed shortcodes, all should work over https, regardless whether they set https argument (to true/false) or not at all.

Reviewers: paulbunkham

Reviewed By: paulbunkham

Subscribers: mdawaffe, paulbunkham, jblz

Tags: #touches_jetpack_files

Differential Revision: D16996-code

This commit syncs r179447-wpcom.

Proposed changelog entry for your changes:

Updated Wufoo Shortcode to always load over https and use async form embed.

[jetpackbot]

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[mdawaffe]

Code looks reasonable. Do you have any specific tests I can try? I don't have a wufoo account. What URLs were you testing?

[marekhrabe]

[wufoo username="marekhrabe" formhash="zoz5s8o0qrgkec" autoresize="true" height="260" header="show" ssl="true"]

Wufoo now appends ssl="true" but that's not the case for many embeds generated in the past and they are missing that param forcing the old behavior to load over HTTP.

Some more forms (that I don't own so never submit!) 1ef08-pb

[mdawaffe]

Thanks! Looks good.