Create new rule for warning about Default Charset UTF-8 in Content-Type Header

Charset UTF-8 in Content-Type Header is in EAP 7.1 now set as default.

When:
If a resource method returns a Text media type without an explicit charset, Resteasy will add "charset=UTF-8" to the returned Content-Type header.
@Produces("text/*")
or
@Produces("application/xml*")

Perform:
Warn about default UTF-8 charset and suggest to set resteasy.add.charset to false in web.xml <context-param> if the functionality is not wanted.

Links:

• https://access.redhat.com/documentation/en-us/red_hat_jboss_enterprise_application_platform/7.1.beta/html/migration_guide/application_migration_changes#migrate_additonal_resteasy_changes
• http://docs.jboss.org/resteasy/docs/3.1.4.Final/userguide/html_single/index.html#Text_media_types