Pressbooks LTI provider exports CC 1.1 properly but labels the file as XHTML

Prerequisites

[x] Can you reproduce the behavior you wish to address with all plugins except Pressbooks and this plugin deactivated?
[x] Are you running the latest version of Pressbooks, the latest version of this plugin and the latest version of WordPress?
[x] Did you perform a cursory search to see if your bug or enhancement is already listed?

Description

When exporting LTI common cartridge 1.1, export file gets labeled as XHTML.

Steps to Reproduce

Set export CC 1.1 for Moodle
Export Thin CC 1.1
See that cartridge is labeled XHTML, but when it is downloaded it is still an .imscc and does import into Moodle properly.

Expected behavior:

I'd export the CC file to be labeled as the file type and the version

Actual behavior:

The file is labeled XHTML.

System Information

Book Info

Book ID: 15 Book URL: http://oer.ed-beck.com/forallx/ Book Privacy: Public

Browser

Platform: OS X Browser Name: Chrome Browser Version: 66.0.3359.139 User Agent String: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.139 Safari/537.36

WordPress Configuration

Network URL: http://oer.ed-beck.com/ Network Type: Subdirectory Version: 4.9.6 Language: en_US WP_ENV: production WP_DEBUG: Disabled Memory Limit: 5000M

Pressbooks Configuration

Version: 5.3.0 Book Theme: Jacobs Book Theme Version: 1.0.0 Root Theme: Aldine Root Theme Version: 1.3.0

Pressbooks Dependencies

Epubcheck: Installed Kindlegen: Installed xmllint: Installed PrinceXML: Installed Saxon-HE: Installed

Must-Use Plugins

hm-autoloader.php: n/a

Network Active Plugins

GitHub Updater: 7.6.2 Openstax Import for Pressbooks: 1.2.0 Pressbooks: 5.3.0 Pressbooks LTI Provider: 0.4.0 Pressbooks Stats: 1.4.1

Book Active Plugins

WP QuickLaTeX: 3.8.4 Wp Show Site ID: 1.0.0

Inactive Plugins

Akismet Anti-Spam: 4.0.3 Candela Links: 0.1 Candela LTI: 0.1 Candela Thin Exports: 0.1 CC Export for Pressbooks: 0.2.1 Docraptor for Pressbooks: 2.2.1 H5P: 1.10.2 Hello Dolly: 1.6 Hypothesis: 0.5.0 LTI: 0.1 mPDF for Pressbooks: 3.1.2

Server Configuration

PHP Version: 7.0.30-0ubuntu0.16.04.1 MySQL Version: 5.7.22 Webserver Info: Apache/2.4.18 (Ubuntu)

PHP Configuration

Safe Mode: Disabled Memory Limit: 5000M Upload Max Size: 2000M Post Max Size: 2000M Upload Max Filesize: 2000M Time Limit: 30 Max Input Vars: 1000 URL-aware fopen: On (1) Display Errors: N/A

PHP Extensions

OPcache: Zend XDebug: Disabled cURL: Supported cURL Version: 7.47.0 imagick: Installed xsl: Installed

pressbooks / pressbooks-lti-provider