Fix issues with Cascading 2.5

[kkrugler]

Jeremy Davis reported a problem with DirectoryTap (see stack trace below). I've made some progress on fixing this, but more work remains.

java.lang.IllegalArgumentException: Path provided doesn't exist: build/test/KryoSchemeTest/testFieldSelection/dst
at com.scaleunlimited.cascading.local.DirectoryTap.getTaps(DirectoryTap.java:121)
at com.scaleunlimited.cascading.local.DirectoryTap.resourceExists(DirectoryTap.java:200)
at com.scaleunlimited.cascading.local.DirectoryTap.resourceExists(DirectoryTap.java:34)
at cascading.flow.BaseFlow.deleteOrFail(BaseFlow.java:1013)
at cascading.flow.BaseFlow.deleteSinksIfReplace(BaseFlow.java:1043)
at cascading.flow.local.LocalFlow.internalStart(LocalFlow.java:111)
at cascading.flow.BaseFlow.start(BaseFlow.java:794)
at cascading.flow.BaseFlow.complete(BaseFlow.java:854)
at com.scaleunlimited.cascading.local.KryoSchemeTest.testFieldSelection(KryoSchemeTest.java:244)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:76)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
at org.junit.runner.JUnitCore.run(JUnitCore.java:157)
at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:63)