Add Czech (qwerty) keymap.

BUG=rhbz#1074879

Review URL: https://codereview.appspot.com/74520044
Update supported vala version to 0.20.

Review URL: https://codereview.appspot.com/76830043
Send panel input purpose.

gnome-shell gets input purpose so that disables IME with password mode.

Review URL: https://codereview.appspot.com/81770044
Keep track of content-type change after focus-in

This is an amendment to 6ca5ddb3.  As content-type (input-purpose and hints)
can change after focus-in, we should monitor the changes.

BUG=
R=takao.fujiwara1@gmail.com

Review URL: https://codereview.appspot.com/83920043
Fix leak in ibus_get_local_machine_id()

If /var/lib/dbus/machine-id does not exist but /etc/machine-id exists,
'error' will be set but will never be freed.

BUG=http://code.google.com/p/ibus/issues/detail?id=1701

Review URL: https://codereview.appspot.com/88770043
Patch from Christophe Fergeau <cfergeau@redhat.com>.
Change deprecated GtkHButtonBox to GtkButtonBox in ibus-setup.

Review URL: https://codereview.appspot.com/88850043
Do not show property panel by default.

Property panel sometimes hides text entry box on firefox in case
the mode is auto-hide because firefox does not provide the right
cursor locations and firefox does not update cursor locales
when preedit is updated so property panel hides text entry box
for a while and auto-hide is not useful with firefox and thunderbird.

TEST=gsettings reset org.freedesktop.ibus.panel show

Review URL: https://codereview.appspot.com/90480043
Do not move property panel with focus-in in case panel is always shown.

Review URL: https://codereview.appspot.com/98770043
Update translation zh_CN.po

Review URL: https://codereview.appspot.com/96740044
Release 1.5.7

Review URL: https://codereview.appspot.com/96800043