Build various components with correct log domain

We were using invalid flags here and there.

Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>
common: Don't close stderr in test-transport

This causes very hard to debug problems.

Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>
common: Make our own g_test_expect_message() work around

The g_test_expect_message() until 2.40 was pretty broken, so
build our own. This way we can start to quiet down our tests.

See: http://bugzilla.gnome.org/show_bug.cgi?id=661926
Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>
common: Remove cockpit_log_null_handler

We're not using it, and should really be using our
cockpit_test_expect_message() in our tests.

Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>
common: Further quietening down of tests

Use our new cockpit_test_expect_xxx() funcitons to quieten down
the tests further. In addition in websocket, since we can't depend
on cockpit, use another work around.

Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>
web: Quieten down the expected failures in web tests

Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>
common: Move repetetive test init stuff into cockpit_test_init

Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>
common: Add new cockpit_assert_strmatch() function

Remove duplicate definitions of assert_matches() macro.

Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>
common: Consolidate into cockpit_test_skip()

Since we can't call g_test_skip() yet, it's not available in
the GLib's we target, make a single copy of our own function.

Closes #471
Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>