version to 0.1.0

* some cleanups and tweaks from actually using the CLI (#20)
* have an ENV var drive what file the CLI loads to configure Dassets (#18)
* system testing the middleware when used in an actual Rack app (#17)
* rack middleware for serving asset files (#15)
* adding file related attrs to asset file model (#14)
* Dassets index operator for looking up asset files by path (#13)
* removing unnecessary Digests singleton; null pattern on digests (#12)
* replace JSON digests file encoding with custom CSV-like encoding (#11)
* cache command for writing out fingerprinted asset files (#6)
* asset file rework (#5)
* digest command (#4)
* model the asset file (#3)
* model the digests file and allow updating and saving changes (#2)
* Design and setup (#1)