Remove hardcoded maven settings.xml ref

Summary:
This stops ant build from succeeding since settings.xml not bundled with
linkbnech.

Proxy settings can be configured globally e.g. with $HOME/.ant/settings.xml

Test Plan: ant succeeds in compiling

Reviewers: emayanke, dhruba

Reviewed By: emayanke

Differential Revision: https://reviews.facebook.net/D8295

README.md

@@ -90,7 +90,7 @@ or Mac OS X.
       Java runtime version.  You will also need a Java JDK to compile from source.
 
 **Ant**: To build LinkBench, you will need the Apache Ant build tool. If
-    you do not have it already, it is available from http://ant.apache.org
+    you do not have it already, it is available from http://ant.apache.org .
 
 **MySQL Connector**:  To benchmark MySQL with LinkBench, you need MySQL
     Connector/J, A version of the MySQL connector is bundled with
@@ -116,6 +116,10 @@ If the build is successful, you should get a message like this at the end of the
     BUILD SUCCESSFUL
     Total time: 3 seconds
 
+If the build fails while downloading required files, you may need to configure Maven,
+for example to use a proxy.  Example Maven proxy configuration is shown here:
+http://maven.apache.org/guides/mini/guide-proxies.html
+
 Now you can run the LinkBench command line tool:
 
     ./bin/linkbench

build.xml

@@ -135,7 +135,7 @@
     <artifact:remoteRepository id="fbnexus" url="${mvn.fb.repo}"/>
 
     <!-- Download the dependencies -->
-    <artifact:dependencies filesetId="build-dependency-jars" settingsFile="${basedir}/settings.xml">
+    <artifact:dependencies filesetId="build-dependency-jars">
       <pom file="pom.xml"/>
     </artifact:dependencies>