Make all SqlResult methods close the ResultSet when finished

Before the previous commit, it perhaps made sense for these methods to
not close the ResultSet—the SqlResult exposed methods to iterate through
the results one-by-one, and these methods only deal with the current
row.

relate/src/main/scala/com/lucidchart/relate/SqlResult.scala

@@ -50,12 +50,8 @@ class SqlResult(private[relate] val resultSet: java.sql.ResultSet) extends Colle
   }
 
   def asScalar[A](): A = asScalarOption.get
-  def asScalarOption[A](): Option[A] = {
-    if (resultSet.next()) {
-      Some(resultSet.getObject(1).asInstanceOf[A])
-    } else {
-      None
-    }
+  def asScalarOption[A](): Option[A] = withResultSet { resultSet =>
+    Option.when(resultSet.next())(resultSet.getObject(1).asInstanceOf[A])
   }
 
   /**

relate/src/test/scala/SqlResultSpec.scala

@@ -256,6 +256,27 @@ class SqlResultSpec extends Specification with Mockito {
 
       result.asScalarOption[Long] must_== None
     }
+
+    "close the ResultSet" in {
+      val (rs, _, result) = getMocks
+
+      rs.next returns true
+      rs.getObject(1) returns (2: java.lang.Long)
+
+      result.asScalar[Long] mustEqual 2L
+
+      there was one(rs).close()
+    }
+
+    "close the ResultSet if it was empty" in {
+      val (rs, _, result) = getMocks
+
+      rs.next returns false
+
+      result.asScalarOption[Long] must beNone
+
+      there was one(rs).close()
+    }
   }
 
   "extractOption" should {