Move RPC assembly to compile step

For some reason, my codeserver would occasionally create incorrect (stale?) .rpc files for DevMode after running `mvn clean compile`. Running `mvn clean package` would somehow fix this. I am hoping that moving the RPC assembly to the `package` step will prevent this from happening.

The error in the RPC response would read "Type name elision in RPC payloads is only supported if the RPC whitelist file is used." and the client could not deserialize it. I noticed that the .rpc file names generated by `mvn package` differed from those generated by `mvn compile`, so I am assuming this assembly step accounts for the difference.

pom.xml

@@ -327,8 +327,8 @@
         </configuration>
       </plugin>
 
-      <!-- We use this assembly to package the GWT RPC dependencies so they 
-				are aviablible fore integration testing. -->
+      <!-- We use this assembly to compile the GWT RPC dependencies so they
+				are available for integration testing. -->
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-assembly-plugin</artifactId>
@@ -342,7 +342,7 @@
           <execution>
             <id>make-assembly</id>
             <!-- this is used for inheritance merges -->
-            <phase>package</phase>
+            <phase>compile</phase>
             <!-- bind to the packaging phase -->
             <goals>
               <goal>single</goal>