Stats: Update JS and GIF domains

Load stats files from cookie-less stats.wp.com and pixel.wp.com domains to
speed up page load.
Merge pull request #812 from xyu/stats-update-domains

Stats: Update JS and GIF domains
REST API: Fix OAuth process.

The OAuth registration process was failing for sites where site_url was
a subfolder.
REST API: Use set_url_scheme.

Use set_url_scheme instead of doing it manually. props @georgestephanis
Sync: Force privacy check before bulk syncs

The publicly accessible status of sites is checked only when requested and
then cached. This is sometimes a problem with a site changes from private
to public. If we are going to reindex the site we should make sure that we
have the most up-to-date setting.
Merge pull request #818 from xyu/issue-817

Sync: Force privacy check before bulk syncs
No module actions in production if not connected.

Hide the module activate/deactivate and configure options on the module modals when not in dev mode and the user is not connected.
Merge pull request #822 from Automattic/disable-module-actions-when-not-connected

No module actions in production if not connected.
Update the translation to match the current state of the page.
Carousel: set the conditional Style IE styles instead of PHP browser check
Carousel: better IE8 stylesheet
Prefer straight concatenation.

See:
https://github.com/Automattic/jetpack/commit/c8720e351420528693e41880db0
35526201a9f7e#commitcomment-6963582
Readmill Widget: fix typo
Jetpack: Resolve modules not autoactivating glitch

If the ‘version’ option was set to an old version after registration
completed, modules would get gimmicked internally, and only auto
activate ‘new’ modules.  By making sure the version is set correctly
before the connection mechanism runs, we can avoid this.

To duplicate the problem, revert this change set (or make the
`maybe_set_version_option` function return without doing anything), run
the following via wpcli, and reconnect:

```
wp plugin deactivate jetpack
wp option delete jetpack_active_modules
wp option set jetpack_activated 1
wp option delete jetpack_log
wp option update jetpack_options
'{"version":"2.9.3:1404065229","old_version":"2.9.3:1404065229"}'
--format=json
wp plugin activate jetpack
```
Merge pull request #827 from Automattic/bug/auto-activate-glitch

Jetpack: Resolve modules not autoactivating glitch
Improved translation

- Putting a sentence together from multiple, concatenated  partial
strings leads to poor translation outcomes.
Widget readmill: also improved translation.
Carousel: remove space
Network Settings: translate notification
network settings: add esc_url