Spanish translation update

Spanish translation extended and improved.
Duplicate capability hook
SKU: search case insensitive support

As committed in master as well: https://github.com/woothemes/woocommerce/commit/a93cee0cbac395800e9276c596a6329f9968d6c9
Cast term_id as int before using in has_term

As committed in master branch: https://github.com/woothemes/woocommerce/commit/7a21dacf5ba7b6a34468014b0e04b13a34f572c5
Added previous two changes to changelog
RUB currency symbol fixes

As done on master branch:
- https://github.com/woothemes/woocommerce/commit/683d54f957cf4437a213fa8483b580ddae9a5596
- https://github.com/woothemes/woocommerce/commit/1671b1d713f0af4f6a779e85deec005aebd8e98f
esc_js for translatable string in the javascripts

As on master branch:
- https://github.com/woothemes/woocommerce/commit/ba923875a20b66292d4b5c2a4f492506cb4a4a99
- https://github.com/woothemes/woocommerce/commit/3f1bca59ccf006480447d24cec7bbdb4cd7619a1
More esc_js action to prevent errors with translations

As committed on master branch:
- https://github.com/woothemes/woocommerce/commit/38d892b14e26df435e90b2f13f48693d28bc23d4
Update ro_RO frontend translations
Updated the correct doc block for return type
PayPal button should use 'button' and 'alt' classes.

As committed on master:
- https://github.com/woothemes/woocommerce/commit/00cbde04e5585aa36a3622709d38a87a66ce8757
Updated the return doc block with a brief explanation of the return type.
Make date in Customers Order Notes localized

Added missing localization code to line 37.
new status reporting system

new status reporting system, this plugin list is better visually and
very better to read
Have the remove_taxes() method set subtotal to subtotal_ex_tax

As committed on master branch:
- https://github.com/woothemes/woocommerce/commit/742cd3ae364243bdd4e2108d0c10a3458f4893f9
Allow layered nav to work with non pa_ prepended taxonomies

As committed on master branch:
- https://github.com/woothemes/woocommerce/commit/f49bd2cd771d6de3a349a2c882b40c65b56f8eba
Better backwards compatibility with _woocommerce_exclude_image

As committed on master branch:
- https://github.com/woothemes/woocommerce/commit/59db08d70bb3f3f292c5d49e132179ed891f251d
Fix for 0 sale price not returning true in is_on_sale

As committed on master branch:
- https://github.com/woothemes/woocommerce/commit/97ad6e0cda1daf31579b75f464fba9b135ba3549
Splitting the CSS #2785
Merge pull request #3106 from a1ur3l/master

Update ro_RO translation