Update settings labels

[mattstein]

Description

Minor tidying of settings and their labels, submitted as a PR just in case my sendCartInfo label adjustment is too bold.

• Improves sendCartInfo label. (Removes lowercase “commerce”, replaces “gateway” with “PayPal” since that seems pretty safe here.)
• Fixes template spacing.
• Consistently title cases setting labels.
• Uses single quotes for user-facing strings.