mod_authentication: Refactor twitter/facebook logon and signup code.

Now uses a popupwindow for the authentication.
Twitter and Facebook settings are combined in the admin underneat the 'Auth' menu.
Authenticated users are immediately signed up, no extra checks.

(cherry picked from commit 1c1f7b3c3b9905741a171f9a5439b181e0a918a1)

Conflicts:
	modules/mod_facebook/templates/_admin_authentication_service.tpl
	modules/mod_twitter/templates/_admin_authentication_service.tpl
mod_authentication: export send_reminder/2 and lookup_identities/2.

This for convenience of some other auth implementations.
Closes #876

(cherry picked from commit 55d442324a80d12c1c760c86e4d004305a164d47)
(cherry picked from commit 5656b5835c2ab865566f6101cd515d99b408d4a7)
media/embed: fixes for twitter streaming, added notifications for importing and analyzing fetch url media-data.

(cherry picked from commit 73a82fe596cdfade45e70932c6d9fe7685a26876)

Conflicts:
	modules/mod_twitter/templates/_admin_authentication_service.tpl
	rebar.config.lock
mod_search: allow dates like 'now' and '+2 weeks' in search questions.

(cherry picked from commit 7f8bd8e298873a58eb3b8f22a4e48cc1ca61295a)
mod_admin: return the correct context in controller_admin_media_preview

(cherry picked from commit 52f20040102b073b1be2af7997a4098c35dff535)
mod_translation: add more rtl languages.

(cherry picked from commit aa5dcb585ebe5ed4f21c1bc6af746be898da0332)
mod_twitter: fix edoc problem.

(cherry picked from commit 6cd0d093bc1aec18d103d2df9569af7931fd11c6)
(cherry picked from commit 768ce0c9148f9ff77d626dd1eac439d4e6614c17)
mod_oembed: don't display the media twice in the admin

(cherry picked from commit c8e8050badbd3fe2c958b8532cb76e099a20211f)
mod_oembed: add missing fallback _oembed_embeddable.tpl

(cherry picked from commit 504258cad53585f30c09c8c963d0ff7f4b1a7a11)
mod_oembed/mod_twitter: prefer our own 'website' extraction above oembed links. Pass the tweet url in the import_resource notification

(cherry picked from commit db1556ee4c5ea8ed5fb3cad90fac3a9694d23e79)
mod_twitter: fix import of tweets with special-html chars, was double escaped in title.

(cherry picked from commit 228767b2309c382daf24962f3bafdb6268e6241d)
mod_admin: always show media content, independent if size was defined.

(cherry picked from commit ecb83bba5377a62a1419cd59f0c98178689db1f7)

Conflicts:
	modules/mod_admin/templates/_admin_edit_media.tpl
mod_oembed: sanitize received oembed code html and texts.

(cherry picked from commit d83416a1570d4f46d932a43062741d1eaf1c5e86)

Conflicts:
	modules/mod_oembed/mod_oembed.erl
core: add instagram js and urls to whitelist.

(cherry picked from commit 3427c0353bd530afea2f9f2147da4b17db633852)
core: lock new z_stdlib library. Fix twerl git url. Fixes #895

(cherry picked from commit e0034353daacd8ad67b96df6248db45e9e57466e)