[HUDI-476]: Add hudi-examples module (#1151)

add hoodie delta streamer mock source example and dfs source and kafka source examples

Signed-off-by: dengziming <dengziming1993@gmail.com>

add defaultSparkConf utils method

change version of hudi-examples to 0.5.2-SNAPSHOT
change the artifcatId of hudi-spark and hudi-utilities
alter some code to adapt kafka2.0

Update scritps

Add license

pom.xml

@@ -51,6 +51,7 @@
     <module>packaging/hudi-timeline-server-bundle</module>
     <module>docker/hoodie/hadoop</module>
     <module>hudi-integ-test</module>
+    <module>hudi-examples</module>
   </modules>
 
   <licenses>
@@ -267,6 +268,15 @@
           <artifactId>maven-jar-plugin</artifactId>
           <version>${maven-jar-plugin.version}</version>
         </plugin>
+        <plugin>
+          <groupId>net.alchim31.maven</groupId>
+          <artifactId>scala-maven-plugin</artifactId>
+          <version>${scala-maven-plugin.version}</version>
+        </plugin>
+        <plugin>
+          <groupId>org.apache.maven.plugins</groupId>
+          <artifactId>maven-compiler-plugin</artifactId>
+        </plugin>
         <plugin>
           <groupId>org.jacoco</groupId>
           <artifactId>jacoco-maven-plugin</artifactId>