Add Tags.tagIsNumeric and associated SSE builder (JENA-512)

git-svn-id: https://svn.apache.org/repos/asf/jena/trunk@1514086 13f79535-47bb-0310-9956-ffa450edef68
Add unit tests for isNumeric case (JENA-512)

git-svn-id: https://svn.apache.org/repos/asf/jena/trunk@1514087 13f79535-47bb-0310-9956-ffa450edef68