Add basic compatibility with IMGAPI v2

[mguegan]

Changes include :

• s/datasets/images/g
• s/"/'/g
• ping/pong compatibility
• sending dataset logic
• Added Content-MD5 header

Your templates have to be in this form :

<serve_dir>
               \  <dataset - uuid>
                                       \ - file
                                       | - manifest.json

[nshalman]

Cool! I have a branch with some code I found where someone else did something similar that I was hacking on but never pushed. I'll take a look at your code some time this week!

[mguegan]

Well.. I have to admit I'm not convinced by my code, specially the MD5 part... Don't hesitate to beautifying it !