common: Ignore zero byte data blocks in cockpit_pipe_write()

It doesn't make sense to write zero bytes to a stream, and
the logic in dispatch_output() isn't ready for it.

Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>
ws: Clear input data POSTed to web server before freeing

This data may contain passwords and such.

Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>
ws: No threading or blocking in CockpitAuth

To do this we treat login separately from loading cookies. This was
already the case, but we make it clearer.

Actual PAM authentication happens in cockpit-session, so we simply
get notified when it completes and then complete the async login
web response.

There's room to make this cleaner, but will wait until we get GSSAPI
authentication in the mix before refactoring it further.

Closes #557
Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>
Cleanup the G_LOG_DOMAINS we use especially for debugging

 * cockpit-protocol: low level stuff, very busy repetetive messages
   produced by both cockpit-ws and cockpit-agent processes
 * cockpit-ws: web service higher level
 * WebSocket: the web socket code (separate from cockpit)
 * cockpit-agent: the agent specific code

You'll likely need to 'make clean' after applying this patch.

Closes #569
Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>
test: Remove *.pyc files when doing 'make clean'

git can confuse python, which checks the last modified date
of the pyc file.

Closes #570
Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>
ws: G_LOG_DOMAIN fixes for clang

It seems that clang expands nested macros differently than gcc
so we need to redefine G_LOG_DOMAIN earlier in some cases.

Closes #569
Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>
static: Serve static files from a separate directory

These are files that will remain unauthenticated and retrieved
directly from the server connected to.

These files are served in such a way that they are cached for
a year, and not refreshed. They must be renamed when they are
updated.

Closes #561