Add resolve module

[nicholasbishop]

This module will contain a revamped version of path_to_inode, with proper handling for ".." and symlinks.

For this initial commit, just add FollowSymlinks, which will control how symlinks are resolved. For why this is needed, see the difference between fs::metadata and fs::symlink_metadata:

• https://doc.rust-lang.org/std/fs/fn.metadata.html
• https://doc.rust-lang.org/std/fs/fn.symlink_metadata.html