Add a way to fingerprint bitbucket version. (#1810)

Sorry, I don't have a publicly exposed version to provide a showcase,
but here is the relevant snippet:

```html
 /></span></span><a href="/projects/IN" title="CLIENT" data-project-id="1">CLIENT</a></span><span class="repository-name"><a href="/projects/IN/repos/testjenk/browse" data-repository-id="2">testJenk</a></span></td></tr></tbody></table></section><!-- .aui-page-panel-content --></div><!-- .aui-page-panel-inner --></div><!-- .aui-page-panel --></section><!-- End #content --><!-- Start #footer --><footer id="footer" role="contentinfo"><section class="notifications"></section><section class="footer-body"><ul><li data-key="footer.license.free.eval">Git repository management powered by a free <a href="http://www.atlassian.com/software/bitbucket/">Atlassian Bitbucket</a> evaluation license</li></ul><ul><li>Atlassian Bitbucket <span title="9d5666b3b525f078f32c5b9a9c9a75f382c5269c" id="product-version" data-commitid="9d5666b3b525f078f32c5b9a9c9a75f382c5269c" data-system-build-number="9d5666b"> v5.4.0</span></li><li data-key="footer.links.documentation"><a href="http://docs.atlassian.com/bitbucketserver/docs-054/Bitbucket+Server+documentation?utm_campaign=in-app-help&amp;utm_medium=in-app-help&amp;utm_source=stash" target="_blank">Documentation</a></li><li data-key="footer.links.contact.support"><a href="https://support.atlassian.com/contact" target="_blank">Contact Support</a></li><li data-key="footer.links.jac"><a href="https://jira.atlassian.com/browse/BSERV" target="_blank">Request a feature</a></li><li data-key="footer.links.about"><a href="/about">About</a></li><li data-key="footer.links.contact.atlassian"><a href="http://www.atlassian.com/company/contact/" target="_blank">Contact Atlassian</a></li></ul><div id="footer-logo"><a href="http://www.atlassian.com/" target="_blank">Atlassian</a></div></section></footer><!-- End #footer --></div><script>require('bitbucket/internal/layout/base/base').onReady(null, "Bitbucket" ); require('bitbucket/internal/widget/keyboard-shortcuts/keyboard-shortcuts').onReady();</script><script>require('bitbucket/internal/page/global-repository-list/global-repository-list').onReady('#repositories-table');</script></body></html>
```

src/apps.json

@@ -736,6 +736,7 @@
 			"env": "^bitbucket$",
 			"icon": "Atlassian Bitbucket.svg",
 			"implies": "Python",
+      "html": "<li>Atlassian Bitbucket <span title=\"[a-z0-9]+\" id=\"product-version\" data-commitid=\"[a-z0-9+]\" data-system-build-number=\"[a-z0-9]+\"> v([\\d.]+)<\\;version:\\1</span>",
 			"meta": {
 				"application-name": "Bitbucket"
 			},