PARQUET-1589: Bump Java to 1.8 (#134)

diff --git a/pom.xml b/pom.xml
index 2fb17f3..3679c82 100644
--- a/pom.xml
+++ b/pom.xml
@@ -83,8 +83,8 @@
   </developers>
 
   <properties>
-    <maven.compiler.source>1.6</maven.compiler.source>
-    <maven.compiler.target>1.6</maven.compiler.target>
+    <maven.compiler.source>1.8</maven.compiler.source>
+    <maven.compiler.target>1.8</maven.compiler.target>
     <shade.prefix>shaded.parquet</shade.prefix>
     <thrift.executable>thrift</thrift.executable>
     <thrift.version>0.9.3</thrift.version>