doc: Replace mentions of make-ring.py by build.py.

* README.rst <make-ring.py>: Replace by build.py.
* docs/source/dev/compiling_and_installing/ring-project.rst: Likewise.
* build.py: Replace 'Ring' by 'Jami'.

Change-Id: I0231ddf541b2622f6042a12ed3ac7ad724b317ae