ws: Add a /ping REST request for checking if cockpit is running

We implement unrestricted CORS on /ping which allows callers
embedding Cockpit to check if it is running on a given server
before trying to embed it.

From a security perspective, there are *many* other ways to check
if Cockpit is running on a particular server from a third-party
website such as loading an image or script from Cockpit. This
does not weaken security, simply enables the correct approach
for doing such a check.

Fixes #602
Closes #743
Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>
ws: Make favicon test work with other branding

Other branding doesn't have the same exact content length for
favicon.

Closes #744
Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>
shell: Change "RAID Array" to "RAID Device"

Fixes #725
Closes #745
Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>
make journal date picker big enough to fit menu entrys

Reviewed-by: Patrick Uiterwijk <puiterwijk@redhat.com>
Fixes #742
Closes #753
Ignore the test results
shell: Implementing searching and pulling docker images

Fixes #373
Fixes #370
Signed-off-by: Stef Walter <stefw@redhat.com>
 * Fixed whitespace issues
shell: Move some docker pull related things around

Reviewed-by: Stef Walter <stefw@redhat.com>
shell: Add docker pull tag text field

Reviewed-by: Stef Walter <stefw@redhat.com>
shell: Show docker pull errors and tag text

Reviewed-by: Stef Walter <stefw@redhat.com>
shell: Fix styling and placement of docker pull tag field

Reviewed-by: Stef Walter <stefw@redhat.com>
shell: Styling for active docker pull class

Reviewed-by: Stef Walter <stefw@redhat.com>
shell: Mark the selected row as active in docker pull dialog

Reviewed-by: Stef Walter <stefw@redhat.com>
shell: Show more progress and use the .stream and .done callbacks

Reviewed-by: Stef Walter <stefw@redhat.com>
shell: Make only downloading docker layers show

Reviewed-by: Stef Walter <stefw@redhat.com>
shell: Fix image location in docker pull

Reviewed-by: Stef Walter <stefw@redhat.com>
shell: Remove the docker download_fail event

Closes #600
Reviewed-by: Stef Walter <stefw@redhat.com>
agent: Eliminate the possible use of NULL pointer

Fixes #717
Closes #749
Signed-off-by: Stef Walter <stefw@redhat.com>
 * Rename test and cleanup whitespace
shell: Moves name field to top of RAID dialog

Fixes #726
Closes #750
Reviewed-by: Stef Walter <stefw@redhat.com>
static: Login screen descriptive error on failed login

Fixes #673
Closes #748
Signed-off-by: Stef Walter <stefw@redhat.com>
 * Whitespace fix
cockpit: All processes and  tests ignore SIGPIPE.

Make sure all processes and tests (except for some testing mock processes) ignore SIGPIPE.

Fixes #716