Makefile.am: Fixed update-po target, updated po/POTFILES.in, removed po/POTFILES, added po/rolekit.pot
Define MISSING_CHECK error type

Used in both DBusRole.Set and RoleBase.Set.
Fix a typo in Role[Kk]itError
Fix a copy/paste error, undefined symbol “x”
Silence a warning about an undefined variable

  a = undefined_variable_name
is way too obvious for static analysis tools to detect; if we want
to raise an exception, use something rarer.

This doesn’t change behavior of the test code; the log in /tmp/log
handles both NameError and ZeroDivisionError in the same way.

Eventually, we might end up just with an explicit
  raise SomeExceptionType
but that’s a less realistic test code, so let’s not do it just now.
Fix undefined references to b2u

This function exists in rolekit.functions, but an import was missing.
Fixed states according to Stephens diagram to provide transitional states

- New PERSISTENT_STATES and TRANSITIONAL_STATES list
RoleBase: Handle exceptions only in D-Bus methods
RoleBase: Apply values in deploy and update calls, readonly properties

- New apply_values method to
- New _READONLY_SETTINGS: Properties that can not be changed within a deploy and update call
- New _check_property method that replaces the individual _check_X methods
- New get_property method to have a single access method for properties
- Reworked get_dbus_property, uses get_property
- New error codes UNKNOWN_SETTING and READONLY_SETTING
- More comments
RoleBase: New copy_defaults method
RoleBase: New methods assert_state and change_state, new state UPDATING

- New error code INVALID_STATE
Adapt testrole to latest RoleBase changes
RoleBase: Removed remaining @handle_exceptions for __init__