Bullhorn subscribe by email

[oraNod]

Resolves issue #351

This PR:

• Removes the link on the homepage to the forum RSS feed for bullhorn posts.
• Adds a link on the homepage to the mailchimp subscription form: https://ansible.us19.list-manage.com/subscribe?u=56d874e027110e35dea0e03c1&id=d6635f5420
• Changes the text of the subscribe button on the homepage to "Subscribe by email"
• Changes the icon on the subscribe button from RSS feed to Mailchimp.

Mobile:

[oraNod]

One comment on accessibility here. I was able to navigate the mailchimp form by keyboard and all fields are labeled. Here is the WAVE report: https://wave.webaim.org/report#/https://ansible.us19.list-manage.com/subscribe?u=56d874e027110e35dea0e03c1&id=d6635f5420

There are some higher level page errors but the form itself doesn't have any specific accessibility violations. This seems to indicate to me that users with assistive technology would be able to access the subscribe form and use it as intended.

[tiyiprh]

Looks good! I'm not too sure about using the mailchimp icon on the button though. I feel like it's hard to see and the button is descriptive enough to indicate the action.

[oraNod]

Looks good! I'm not too sure about using the mailchimp icon on the button though. I feel like it's hard to see and the button is descriptive enough to indicate the action.

@tiyiprh Yeah, good call. It's better without that icon.