Implement begining of migration

Move Function/Query definition

src/main/kotlin/fr/postgresjson/connexion/Connection.kt

@@ -1,6 +1,7 @@
 package fr.postgresjson.connexion
 
 import com.fasterxml.jackson.core.type.TypeReference
+import com.github.jasync.sql.db.Connection
 import com.github.jasync.sql.db.QueryResult
 import com.github.jasync.sql.db.pool.ConnectionPool
 import com.github.jasync.sql.db.postgresql.PostgreSQLConnection
@@ -28,6 +29,8 @@ class Connection(
         return connection
     }
 
+    fun <A> inTransaction(f: (Connection) -> CompletableFuture<A>) = connect().inTransaction(f)
+
     fun <T, R : EntityI<T?>?> selectOne(sql: String, typeReference: TypeReference<R>, values: List<Any?> = emptyList()): R? {
         val future = connect().sendPreparedStatement(sql, compileArgs(values))
         val json = future.get().rows[0].getString(0)