dead-end forks identification at github and bitbucket repositories
database: added QueryWithVisibility, and Query hide dead-end forks by default
database: simplier hidden logic
hidding dead-end forks, fixes following @garyburd  guidelines
checking for fork flag
less requests at bitbucket repositories
Merge pull request #197 from mcuadros/endfork

hides and identifies dead-end forks at github and bitbucket repositories