Add bitbucketweb to git browser plugins

[tomasulo]

This adds support for bitbucketweb as a git repository browser. The result is:

<scm... >
    <browser class="hudson.plugins.git.browser.BitbucketWeb">
        <url>
            https://bitbucket.org/url-to-your-repository
        </url>
    </browser>
</scm>

[daspilker]

Replaced by #1049 which adds support for all browsers through the Automatically Generated DSL.

job(String name) {
  scm {
    git {
      browsers {
        bitbucketWeb {
          repoUrl(String value)
        }
      }
    }
  }
} 

[tomasulo]

Awesome, when will this available?