ws: Use private kerberos ccaches

We never want to share kerberos ticket caches with either the root
user (via the kernel keyring or default ccache) or between users
who are both authenticating via cockpit-ws.

 * Prevent use of a default ccache in cockpit-ws
 * Explicitly allocate memory ccache's in cockpit-ws for the
   threads that are authenticating users via libssh
 * Prevent use of a default ccache in cockpit-session

Fixes #1311
Closes #1313
Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>
shell: Reset more storage selectpickers in the right way

So that the UI is also updated.

Closes #1322
Reviewed-by: Stef Walter <stefw@redhat.com>
doc, ws: Move .desktop and .appdata to src/ws

Fixes #1253
Closes #1318
Reviewed-by: Stef Walter <stefw@redhat.com>
Use the term 'package' instead of 'module'

The packages really are just collections of resources, with the actual
html files and javascript files and (soon iframes) providing the actual
modular architecture.

In addition 'modules' is used a lot in the javascript community to do
with module loaders etc. We want to avoid confusion there.

Rename 'module' to 'package' everywhere. And move the modules/ directory
to pkg/ which is shorter and clearer.

Closes #1310