DATACOUCH-341 - Add kotlin extension functions

Motivation
----------
Add kotin extension methods to couchbase and reactive couchbase
operations as required.

Changes
-------
Extensions leveraging reified type has been added.

Results
-------
It is now possible to use reified types rather than passing the java
class reference to some operation functions.

Original pull request: #160.

src/integration/kotlin/org/springframework/data/couchbase/core/CouchbaseOperationsExtensionsTest.kt

@@ -0,0 +1,32 @@
+package org.springframework.data.couchbase.core
+
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.springframework.beans.factory.annotation.Autowired
+import org.springframework.data.annotation.Id
+import org.springframework.data.couchbase.ContainerResourceRunner
+import org.springframework.data.couchbase.IntegrationTestApplicationConfig
+import org.springframework.test.context.ContextConfiguration
+import kotlin.test.assertEquals
+
+@RunWith(ContainerResourceRunner::class)
+@ContextConfiguration(classes = [IntegrationTestApplicationConfig::class])
+class CouchbaseOperationsExtensionsTest {
+
+    @Autowired
+    lateinit var template: CouchbaseTemplate
+
+    @Test
+    fun `findById should call the reified extension`()  {
+        val entityId = "CouchbaseOperationsExtensionsTestFindById"
+        val entity = Entity(entityId)
+        template.save(entity)
+        val stored = template.findById<Entity>(entityId)
+        assertEquals(entity.id, stored.id)
+    }
+
+    class Entity constructor(id: String) {
+        @Id
+        var id = id
+    }
+}

src/integration/kotlin/org/springframework/data/couchbase/core/RxJavaCouchbaseOperationsExtensionsTest.kt

@@ -0,0 +1,35 @@
+package org.springframework.data.couchbase.core
+
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.springframework.beans.factory.annotation.Autowired
+import org.springframework.data.annotation.Id
+import org.springframework.data.couchbase.ContainerResourceRunner
+import org.springframework.data.couchbase.ReactiveIntegrationTestApplicationConfig
+import org.springframework.data.couchbase.core.query.N1qlSecondaryIndexed
+import org.springframework.test.context.ContextConfiguration
+import kotlin.test.assertEquals
+
+
+@RunWith(ContainerResourceRunner::class)
+@ContextConfiguration(classes = [ReactiveIntegrationTestApplicationConfig::class])
+class RxJavaCouchbaseOperationsExtensionsTest {
+
+    @Autowired
+    lateinit var template: RxJavaCouchbaseTemplate
+
+    @Test
+    fun `findById should call the reified extension`()  {
+        val entityId = "RxJavaCouchbaseOperationsExtensionsTestFindById"
+        val entity = Entity(entityId)
+        template.save(entity).toBlocking().single()
+        val stored = template.findById<Entity>(entityId).toBlocking().single()
+        assertEquals(entity.id, stored.id)
+    }
+
+    class Entity constructor(id: String) {
+        @Id
+        var id = id
+    }
+}
+