Add helper for users to add DataFrame#render syntax

And more Toree API compatibility too

modules/almond-spark/src/main/scala/almond/spark/syntax.scala

@@ -0,0 +1,17 @@
+package almond.spark
+
+import almond.display.Html
+import org.apache.spark.sql._
+import org.apache.spark.{SparkConf, SparkContext}
+
+object syntax {
+  implicit class KernelToreeSparkOps(private val kernel: almond.api.JupyterApi) {
+    def sparkContext: SparkContext = sparkSession.sparkContext
+    def sparkConf: SparkConf       = sparkContext.getConf
+    def sparkSession: SparkSession = SparkSession.builder().getOrCreate()
+  }
+  implicit class AlmondNetflixDataFrameOps(private val df: DataFrame) {
+    def render(limit: Int = 10): Html =
+      Html(DataFrameRenderer.render(df, limit = limit))
+  }
+}