refs #2495 Cytoscape version number and target Cytoscape.js version number have neen added to exported JSON (both network and visual style).

(cherry picked from commit 61801d6b0c86250b1578c89a764ac8216daf52c5)
refs #2495 format version has been added.

(cherry picked from commit 3a7133f4510febad61b82b7ab98fe3390212e3d8)
Target version number has been replaced by semver range notation.

(cherry picked from commit 569bd2955db92f8d3b82cd2e7283f34298fce364)