Adding an ability to set target for mysql user grant.

Change-Id: I793a25750c39f70bb26415e7e6a95100b77773fe

README.rst

               password: 'password'
               host: 'localhost'
               rights: 'all privileges'
+              database: '*.*'
 
 Galera cluster slave node
 

galera/server.sls

 mysql_grants_{{ user.name }}_{{ database_name }}_{{ user.host }}:
   mysql_grants.present:
   - grant: {{ user.rights }}
-  - database: '{{ database_name }}.*'
+  - database: {{ user.get('database', database_name + '.*') }}
   - user: '{{ user.name }}'
   - host: '{{ user.host }}'
   - ssl_option: {{ user.get('ssl_option', False) }}