Code-generator always outputs to target/generated-sources

[mach6]

if you bind code-generator to the generate-test-sources phase it should output to the target/generated-test-sources directory. In addition, the plugin should allow the user to override the output location.

Steps to reproduce: Use this xml in the project pom.

<plugin>
  <groupId>com.paypal.selion</groupId>
  <artifactId>SeLion-Code-Generator</artifactId>
  <version>1.0.0</version>
  <executions>
    <execution>
       <phase>generate-test-sources</phase>
       <goals>
         <goal>generate</goal>
       </goals>
    </execution>
  </executions>
</plugin>

[mach6]

fix merged with #287