bugfix: non-project files are compiled

[lukewhrit]

Currently, files such as a project's README.md are attempted to be compiled. This is unwanted behavior as the project should only include specific directories, like posts or pages.

We have two options for solving this problem:

1. Only compile files that are in posts and pages by ignoring all other directories. (Preferred)
2. Ignore all files in the root directory besides layout.html.

I think I'll get to work on implementing the first solution.