installation: mercurial addition

* Adds mercurial to the list of dependencies for installation
  in INSTALL guide after 787b62e8.

Signed-off-by: Jan Aage Lavik <jan.age.lavik@cern.ch>
assets: Flask-Assets update to 0.10.dev

Signed-off-by: Yoan Blanc <yoan.blanc@cern.ch>
assets: requirejs and uglifyjs

* Enables two more filters.

* Enables modular JavaScript applications with AMD structuring.

Signed-off-by: Yoan Blanc <yoan.blanc@cern.ch>