added a call for build with parameters.

See Parameterized Build: https://wiki.jenkins-ci.org/display/JENKINS/Parameterized+Build

eg:

```ruby
1.9.3p194 :009 > @jc.job.build('web-app-tests-branches',{:branch=>'feature/build-with-parameters'})
 => "302"
```
![Screen Shot 2013-02-11 at 10 32 22 AM](https://f.cloud.github.com/assets/15386/145965/689c3b5c-7479-11e2-87a9-f7ea9c268e6a.png)