Implement better fake formats than ???

Fixes sbt/librarymanagement#67
Fixes sbt/sbt#3288

core/src/main/scala/sbt/internal/librarymanagement/formats/GlobalLockFormat.scala

@@ -2,7 +2,24 @@ package sbt.internal.librarymanagement.formats
 
 import sjsonnew._
 import xsbti._
+import java.io.File
+import java.util.concurrent.Callable
 
+/**
+ * A fake JsonFormat for xsbti.GlobalLock.
+ * This is mostly for making IvyConfiguration serializable to JSON.
+ */
 trait GlobalLockFormat { self: BasicJsonProtocol =>
-  implicit lazy val GlobalLockFormat: JsonFormat[GlobalLock] = ???
+  import GlobalLockFormats._
+
+  implicit lazy val globalLockIsoString: IsoString[GlobalLock] =
+    IsoString.iso(_ => "<lock>", _ => NoGlobalLock)
+
+  implicit lazy val GlobalLockFormat: JsonFormat[GlobalLock] = implicitly
+}
+
+private[sbt] object GlobalLockFormats {
+  object NoGlobalLock extends GlobalLock {
+    def apply[T](lockFile: File, run: Callable[T]) = run.call()
+  }
 }

core/src/main/scala/sbt/internal/librarymanagement/formats/LoggerFormat.scala

@@ -2,7 +2,15 @@ package sbt.internal.librarymanagement.formats
 
 import sjsonnew._
 import xsbti._
+import sbt.util.Logger.Null
 
+/**
+ * A fake JsonFormat for xsbti.Logger.
+ * This is mostly for making IvyConfiguration serializable to JSON.
+ */
 trait LoggerFormat { self: BasicJsonProtocol =>
-  implicit lazy val LoggerFormat: JsonFormat[Logger] = ???
+  implicit lazy val xsbtiLoggerIsoString: IsoString[Logger] =
+    IsoString.iso(_ => "<logger>", _ => Null)
+
+  implicit lazy val LoggerFormat: JsonFormat[Logger] = implicitly
 }