Build process and solution file convention

When AppHarbor builds from your repository, we use a convention based approach in selecting which solution to build. Depending on the scenario we'll treat it differently during the build process. These are the conventions that applies to each scenario:

No solution file: The build engine will treat the repository as a WebMatrix project.

A single solution file: The build engine will build the single solution file.

Multiple solution files: The build engine will look for a solution file called "AppHarbor.sln" (case sensitive). If no such file exists it will look for a solution file named as the application's slug (and the ".sln" suffix). If no such file exists you'll get a build error stating that we couldn't pick a single solution file.