Fix uniontype compatibility issue in TweetParser

1. Fix compatibility issue of UnionType in TweetParser.
2. Add unit test for TweetParser, covering missing attribute record
   filtering.

Change-Id: Id7e316d20f929236b3fa17618bb8f87d28ac7efc
Reviewed-on: https://asterix-gerrit.ics.uci.edu/1786
Tested-by: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
BAD: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Integration-Tests: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Reviewed-by: Steven Jacobs <sjaco002@ucr.edu>
diff --git a/asterixdb/asterix-external-data/pom.xml b/asterixdb/asterix-external-data/pom.xml
index ff9fcb0..460f57d 100644
--- a/asterixdb/asterix-external-data/pom.xml
+++ b/asterixdb/asterix-external-data/pom.xml
@@ -170,6 +170,7 @@
             <exclude>src/test/resources/classad/**</exclude> <!-- HTCondor (license in LICENSE file) -->
             <exclude>src/test/resources/record.json</exclude> <!-- https://issues.apache.org/jira/browse/ASTERIXDB-1850 -->
             <exclude>src/test/resources/change_feed.csv</exclude>
+            <exclude>src/test/resources/test_tweets.txt</exclude>
           </excludes>
         </configuration>
       </plugin>