Improve the documentation of requirements

[peterzahemszky]

Currently README.rst doesn't detail the prerequisite packages. In order to avoid problems like issue #570, it would be useful to clarify what version ranges are supported for each dependency.

[peterzahemszky]

A possible alternative is trying to update outdated packages while running make deps.

For example, installing npm is already a responsibility taken up by make deps:

simphony-remote/Makefile

Lines 108 to 113 in fc5f0ae

	npmdeps:
	if [[ `command -v npm` == '' ]]; then \
	sudo $(PKG_MNGR) install -y node-gyp libssl1.0-dev; \
	sudo $(PKG_MNGR) install -y npm; \
	fi