Fix TimeHelpersSpec specs2-related compile issue.

specs2 stopped supporting mixing MatchersImplicits directly into something that
extends Scope, but we can just import the implicits via the MatchersImplicits
singleton.

core/util/src/test/scala/net/liftweb/util/TimeHelpersSpec.scala

@@ -229,7 +229,9 @@ object TimeHelpersSpec extends Specification with ScalaCheck with TimeAmountsGen
   }
 }
 
-object forAllTimeZones extends Around with MatchersImplicits {
+object forAllTimeZones extends Around {
+  import MatchersImplicits._
+
   override def around[T: AsResult](f: => T) = synchronized { // setDefault is on static context so tests should be sequenced
     import collection.convert.wrapAsScala._
     // some timezones for java (used in formatters) and for Joda (other computations) has other offset