deprecate use of Byte[] and Character[] as basic types

[gavinking]

Related to #394, I think we should do something like what we did with java.util.Date, warning users to stay away from the use of the basic types Byte[] and Character[]. I can't really justify why we even put these on the list in JPA 1.0, since there's no natural way to store them on most relational databases. (We intended to store them in a VARBINARY or VARCHAR, under the assumption that array contains no null elements, but then, why not use byte[] or char[] instead?)