Update app/models/key.rb to permit SSH keys of type ecdsa rather than forcing dsa and rsa algorithms.

Apply user project limit only for personal projects. We should not include group projects for user limit

Since masters_projects does not cover most of cases now we use authorized_projects for DeployKey read access

Improve query of authorized_projects. Cache results for authorized_groups, authorized_projects methods

Besides specifying http and https url's as the import-url when creating
a new project, you can now use git://... url's to import via the git
protocol.