Do not store scmPassword in cleartext in goalsAndOptions in build.xml.

A user of this plugin complains that when we sets an SCM password, while it is correctly masked in the build log, it appears in the `build.xml`:

```
<org.jvnet.hudson.plugins.m2release.M2ReleaseArgumentInterceptorAction plugin="m2release@0.12.0"> 
    <goalsAndOptions>-DdevelopmentVersion=1.23-SNAPSHOT -DreleaseVersion=1.22 -Dusername=myUsername -Dpassword=myPassword -Dresume=false release:prepare release:perform -Dgoals=deploy</goalsAndOptions> 
</org.jvnet.hudson.plugins.m2release.M2ReleaseArgumentInterceptorAction>
```