Clean up `ant javadoc` to exclude tests and quickstart sample files.

Test Plan:
Ran `ant clean javadoc` and verified that there were no warnings or errors.
Then viewed `build/javadoc/index.html` in Google Chrome and verified it looks good.

build.xml

diff --git a/build.xml b/build.xml
index 7520c21..551ba06 100644
--- a/build.xml
+++ b/build.xml
@@ -257,11 +257,13 @@
              windowtitle="Buck"
              failonerror="true"
              >
-      <fileset dir="${src.dir}"/>
-      <fileset dir="${test.dir}">
-        <exclude name="**/testdata/**" />
+      <fileset dir="${src.dir}">
+        <exclude name="com/facebook/buck/cli/quickstart/**" />
         <exclude name="**/BUCK" />
-        <exclude name="**/*.properties"/>
+        <exclude name="**/*.iml"/>
+        <exclude name="**/*.py"/>
+        <exclude name="**/*.pyc"/>
+        <exclude name="**/*.sh"/>
       </fileset>
       <link href="http://docs.oracle.com/javase/7/docs/api/" />
       <link href="http://docs.guava-libraries.googlecode.com/git-history/v15.0/javadoc/" />