Fix deactivating wc/cc problem

[ghost]

All Submissions:

• Have you followed the ClassicCommerce Contributing guideline?
• Does your code follow the repo standards?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

Fix code in main classic-commerce.php file to allow deactivating of WC before activating of CC. Change message in html-notice-require-compat-plugin.php to add sentence about deleting WooCommerce not deleting your data.

Closes #165 .

How to test the changes in this Pull Request:

1. Copy the 2 changed files into a test site with both WC and CC installed
2. Deactivate one and activate the other.
3. Repeat. Observe message when activating CC.

Other information:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes, as applicable?
• Have you successfully ran tests with your changes locally?

Changelog entry

Allow deactivating of WC before activating of CC. Add message about deleting WooCommerce not deleting your data.