Issue 41: Added support for Tagging and changed the Numeric <-> String Bijections to use String @@ Rep[Numeric] as proof.
example of lifting String into Option[String @@ Rep[Int]]
getting the tests compiling by adding the correct tags
had to comment these out for the moment, the StringJoinBijection is going to require some more work to support preservation of the tags
tags for the standard String Bijections
tag the URL and UUID bijections in the StringBijectionLaws
Adds "toRep[A]" syntax with import Rep._ to provide the ability to take a naked type and lift it into its Rep if it matches. eg.

scala> "123".toRep[Int]
res2: Option[com.twitter.bijection.package.@@[java.lang.String,com.twitter.bijection.Rep[Int]]] = Some(123)

scala> "123a".toRep[Int]
res3: Option[com.twitter.bijection.package.@@[java.lang.String,com.twitter.bijection.Rep[Int]]] = None
Added some docs and reformatted for project style consistency.
Merge pull request #44 from jedws/biject

Added Tag support and changed the Numeric <-> String Bijections to Numeric <-> String @@ Rep[Numeric]