fixed internal links, tables, CLOUDSTACK-5954

Fixed internal links, forgotten tables and  update-ssl.png file : CLOUDSTACK-5954
add default OS in .gitignore file.

```
$ sphinx-build -b html source build
Running Sphinx v1.2.2
loading pickled environment... done
building [html]: targets for 19 source files that are out of date
updating environment: 0 added, 0 changed, 0 removed
looking for now-outdated files... none found
preparing documents... done
writing output... [100%] virtual_machines                                                                                                                                                    
writing additional files... genindex search
copying images... [100%] _static/images/egress-firewall-rule.png                                                                                                                             
copying static files... done
copying extra files... done
dumping search index... done
dumping object inventory... done
build succeeded.
```