Add atime and mtime preservation

Useful for sass-caching when combined with a configurable / steady OS tempDir.
Add stats times to test files

TODO: Being lazy here, should probably test atime and mtime.
Write files to tmp relative to basepath for easier reading back into the stream

The previous way users needed to know the relative diference between cwd and
base. Waaat, nooo. Now they know that files are always directly in tempDir, and
they can pull out of the compiled folder directly.
Bump package to 0.1.1
Only try to preserve atime and mtime if they exist
Bump package to 0.1.2
Add intermediateDir option
Add tests for customDir
Bump package to 0.1.3