cds: bower-base.json addition

* Removes the big directories in MANIFEST.in.
  It cuts it down off 19M (-57%).

Signed-off-by: Yoan Blanc <yoan.blanc@cern.ch>
Merge pull request #10 from greut/bower-base

cds: bower-base.json addition
Mixer: fixtures substitute.

* Introduces `Mixer` as a substitute of `fixtures` to load demo data
  into the CDS demo site.

Signed-off-by: Esteban J. G. Gabancho <esteban.gabancho@gmail.com>