Add option to open projects directly from link

[smathot]

This issue is somewhat related to #10.

If someone gives you a link to a public project on the OSF, there seems to currently be no way to access the project. The most elegant solution would be to have a 'Open project through URL' button, which would allow you to explore public projects in a read-only way.

[dschreij]

Sounds good, but this isn't easy to make. The ID for a project used in URL does not always correspond to the one used in the API endpoints, so I need to dive into this and see if I can translate one into the other. Another point of consideration is, how would we display this in the OSF explorer? Or differently put, where in the tree do we place the file that is linked (it is not possible to go to the parent of an item in the way that Waterbutler provides the nodes).

[smathot]

Let's keep this in mind, but make it low priority then. #10 seems easier to address, and is also a decent way to open public repositories.