Do not show weird context menu entries in app mode

"Inspect element" and "Send Link by Email" should not be shown in app
mdoe.

https://bugzilla.gnome.org/show_bug.cgi?id=699584
app-mode: Use shared secondary process model for web app mode

External links that might broke the app are opened in a external
browser, so better use a single web process for all web app windows.
file-helpers: Add ephy_file_open_uri_in_default_browser()

Helper function to open the given uri in the default browser
embed: Add ephy_embed_utils_urls_have_same_origin()

Helper function to check if two URLs have the same origin
window: Simplify the code to open external uris in default browser when in app mode

Use ephy_embed_utils_urls_have_same_origin() to check if the target URL
is external or not and ephy_file_open_uri_in_default_browser() to open
the URL in the default browser if it's external.
app-mode: Make sure external links are openend in the default web browser

Some sites like gmail, open external links by first opening an empty
window and then loading the URL in that window. In that case we need to
wait until we know the URL to decide whether to show the window, or open
the request in the default browser.

https://bugzilla.gnome.org/show_bug.cgi?id=658395
window: Ignore new-window-in-tabs setting in application mode

There are no tabs in application mode.

https://bugzilla.gnome.org/show_bug.cgi?id=712402
tests: disable broken cases

A page that doesn't load won't have a proper uri, so disable that.
The about pages, not sure yet, but there's a release to make.
[release] 3.14.1
Add workaround for missing view source mode

We'll open the source in the default text editor instead

https://bugzilla.gnome.org/show_bug.cgi?id=738475
Minor string improvements

Mostly use "website" instead of "web site", as is the case in
documentation.

https://bugzilla.gnome.org/show_bug.cgi?id=738866
Updated Brazilian Portuguese translation
Updated Spanish translation
Added Kazakh translation
Updated Galician translations
Change Finnish translation team web page to l10n.gnome.org
Updated Hebrew translation
Updated Norwegian bokmål translation.
Updated Greek translation
Bump WebKitGTK+ requirements to 2.7.2

We will use the new API added in 2.7.2 like script messages.