removed "Trying to get property of non-object..." error on the edit review/comment page.
Update Bulgarian regions names and codes

Update Bulgarian regions codes according to ISO 3166-2:BG http://en.wikipedia.org/wiki/ISO_3166-2:BG and http://www.statoids.com/ubg.html
Also updated the region names be wrote with latin chars for more universalize and easy translated.
MP6 is dead. Long live the WP admin theme
Merge pull request #4355 from leewillis77/master

MP6 is dead. Long live the WP admin theme
Merge pull request #4343 from claudiosmweb/patch-1

Fix #4338 and #4339
Merge pull request #4342 from claudiosmweb/fix_4337

fix #4337
Merge pull request #4340 from maxrice/rest-api-warning-fixes

Fix warning when accessing coupons created in pre-2.1 installs
Merge pull request #4331 from kloon/fix_cod_thankyou_warning

Fix warning on Thank You page with COD, closes #4320
Merge pull request #4329 from kloon/tweak_rest_api_add_wc_version

Add WooCommerce version to API index route
Merge pull request #4334 from splashingpixels/master

syntax error missing semicolon on product grouped class
Merge pull request #4332 from emzo/responsive-product-tabs

[2.1-beta-2] Fix product details meta box tabs for narrow screens
Removed duplicate description key. Closes #4357
replace a few missed &rarr;'s. closes #4350
Merge pull request #4347 from dimitrov-adrian/patch-8

Update Bulgarian regions names and codes
short description meta box #4356
checkboxes in product data tabs #4356
add gallery images link
Stripped faulty default values of do_action parameters. Closes #4359
Fix checkbox width in product data meta box
Merge pull request #4363 from emzo/product-data-checkboxes

[2.1-beta-2] Fix checkbox width in product data meta box