Add japanese character settings

With this PR, users select default character settings (en and ja). The default settings for Japanese (ja) contains the the default character settings such as FULL_STOP and COMMA for Japanese texts.

As the side effect, the format of the main configuration file was changed. The following example is a settings of japanese text.

    <configuration>
      <validator>sample/conf/validation-conf.xml</validator>
      <lang char-conf="sample/conf/symbol-conf-ja.xml">ja</lang>
    </configuration>

As the above example, configuration contains "lang" block which is for default settings. To override the specified default settings, user can specify the symbol configuration file ("sample/conf/symbol-conf-en.xml") in the above settings. Adding the character settings in the file, users can override the default settings of specified characters.

NOTE: the description on the settings in the manual page (http://document-validator.org/docs/0.1-alpha/configuration.html) should be changed.