Split Postgres platform into Postgres10 & Postgres9 (DDL - generated by default as identity) (#1921)

* Split Postgres platform into Postgres10 & Postgres9

- Use "generated by default as identity" for Postgres10 identity columns

* Add postgres9 migrationtest resources

* Set default back to h2

* Add postgres10 migration test resources

src/main/java/io/ebeaninternal/api/PlatformMatch.java

@@ -0,0 +1,27 @@
+package io.ebeaninternal.api;
+
+import io.ebean.annotation.Platform;
+import io.ebean.util.StringHelper;
+
+public class PlatformMatch {
+
+  /**
+   * Return true if the script platforms is a match/supported for the given platform.
+   *
+   * @param platform  The database platform we are generating/running DDL for
+   * @param platforms The platforms (comma delimited) this script should run for
+   */
+  public static boolean matchPlatform(Platform platform, String platforms) {
+    if (platforms == null || platforms.trim().isEmpty()) {
+      return true;
+    }
+
+    // match on base platform name and platform name
+    for (String name : StringHelper.splitNames(platforms)) {
+      if (name.equalsIgnoreCase(platform.base().name()) || name.equalsIgnoreCase(platform.name())) {
+        return true;
+      }
+    }
+    return false;
+  }
+}