Pickup new xgettext version to fix #3239

[deBhal]

We've updated xgettext-js Automattic/xgettext-js#6. Once we publish that package, this PR picks up the new version

To verify the fix:

1. run make translate in this branch
2. rename calypso-strings.php
3. npm update xgettext-js
4. Run make translate again
5. diff the new calypso-strings.php against the old one.

We want to verify that:

1. We pick up the strings we were missing before (e.g. 'Arts & Entertainment')
2. We keep all the other strings we should.

P.S. I'm on holiday with my family at the moment, but need to get this in before the i18n weekly kit goes out on Monday. If the PR looks good, I'd appreciate having it merged :)

[akirk]

This is the diff, looking good (apparently also catches some other skipped strings)

395,401d394
< __( 'The domain could not be unlocked. Additionally, Privacy Protection could not be disabled. The transfer will most likely fail due to these errors.' ),
< __( 'The domain could not be unlocked. The transfer will most likely fail due to this error.' ),
< __( 'Privacy Protection could not be disabled. The transfer will most likely fail due to this error.' ),
< __( 'An error occurred while trying to send the Domain Transfer code: {{strong}}%s{{/strong}} Please {{a}}Contact Support{{/a}}.' ),
< __( 'An error occurred while trying to send the Domain Transfer code. Please try again or {{a}}Contact Support{{/a}} if you continue to have trouble.' ),
< __( 'The registry for your domain requires a special process for transfers. Our Happiness Engineers have been notified about your transfer request and will be in touch shortly to help you complete the process.' ),
< __( 'We have sent the transfer authorization code to the domain registrant\'s email address. If you don\'t receive the email shortly, please check your spam folder.' ),
805,806d797
< __( 'Transfer Domain' ),
< __( 'It is only possible to transfer a domain after 60 days after the registration date. This 60 day lock is required by the Internet Corporation for Assigned Names and Numbers (ICANN) and cannot be waived. {{learnMoreLink}}Learn more.{{/learnMoreLink}}' ),
1011,1064d1001
< __( 'Arts & Entertainment' ),
< __( 'General Arts & Entertainment' ),
< __( 'Creative Arts & Design' ),
< __( 'Entertainment & Culture' ),
< __( 'Music' ),
< __( 'Movies' ),
< __( 'Photography' ),
< __( 'Style & Fashion' ),
< __( 'Sports & Recreation' ),
< __( 'Business & Services' ),
< __( 'General Business & Services' ),
< __( 'Finance & Law' ),
< __( 'Consulting & Coaching' ),
< __( 'Restaurants & Locales' ),
< __( 'Advertising & Marketing' ),
< __( 'Automotive' ),
< __( 'Real Estate' ),
< __( 'Technology & Computing' ),
< __( 'Hotels & Vacation Rentals' ),
< __( 'Communications' ),
< __( 'Family, Home, & Lifestyle' ),
< __( 'General Family, Home, & Lifestyle' ),
< __( 'Family & Parenting' ),
< __( 'Events & Weddings' ),
< __( 'Home & Garden' ),
< __( 'Food & Drink' ),
< __( 'DIY & Crafting' ),
< __( 'Travel' ),
< __( 'Pets' ),
< __( 'Education & Organizations' ),
< __( 'General Education & Organizations' ),
< __( 'Communities & Associations' ),
< __( 'Non-Profit' ),
< __( 'Religion & Spirituality' ),
< __( 'Special Education' ),
< __( 'High School Education' ),
< __( 'College Education' ),
< __( 'Homeschooling' ),
< __( 'Health & Wellness' ),
< __( 'General Health & Wellness' ),
< __( 'Mental Health' ),
< __( 'Exercise / Weight Loss' ),
< __( 'Men\'s Health' ),
< __( 'Women\'s Health' ),
< __( 'Psychology / Psychiatry' ),
< __( 'Nutrition' ),
< __( 'Writing & Books' ),
< __( 'General Writing & Books' ),
< __( 'Book Reviews & Clubs' ),
< __( 'Humor' ),
< __( 'Fiction & Poetry' ),
< __( 'Author Site' ),
< __( 'Screenwriting' ),
< __( 'Non-fiction & Memoir' ),