Add project creation wizard

@aweiksnar Apologies for the monster PR. This is mostly fleshed out now (everything prior was a stub, so the changes aren't really important), but it looks rough and there are still things to fix (subjects cannot currently have metadata: zooniverse/Panoptes#368). I'd like to get this in now and iterate on it later.

Here's what this adds:

* `/build`, listing your user's projects. (Still needs to list projects owned by groups your user is in)

* `/build/new-project`, walking you through the steps to create a new project. (Needs more robust error handling, a better definition of what's in the manifest file)

* `/build/edit-project/:projectID`, currently just a stub, but this will be where you edit project details.

I know some of these giant components can be broken down. I'll do that when I fill in their details.
does this always override the argument?