Update Guava to 19.0-rc1

Release 19 includes several bug fixes and API updates [1].

- Remove "unchecked" warning suppressions that are no longer
  necessary.

- Replace calls to deprecated Futures.transform() with new
  Futures.transformAsync().

- Use CharMatcher's static factory methods instead of constants
  that will later be deprecated.

[1] https://github.com/google/guava/wiki/Release19

Change-Id: I512ddc6ccf7ebaac0c16557d3b0d62ee1394de37

gerrit-lucene/src/main/java/com/google/gerrit/lucene/LuceneChangeIndex.java

@@ -312,7 +312,6 @@ public class LuceneChangeIndex implements ChangeIndex {
     return schema;
   }
 
-  @SuppressWarnings("unchecked")
   @Override
   public void replace(ChangeData cd) throws IOException {
     Term id = QueryBuilder.idTerm(cd);
@@ -332,7 +331,6 @@ public class LuceneChangeIndex implements ChangeIndex {
     }
   }
 
-  @SuppressWarnings("unchecked")
   @Override
   public void delete(Change.Id id) throws IOException {
     Term idTerm = QueryBuilder.idTerm(id);