Upgrade dependencies; bump required node.js version

[lxe]

 ip-address      4.0.0  →    5.8.9
 istanbul      ^0.3.13  →   ^0.4.5
 jshint          2.4.2  →    2.9.5
 path         ^0.11.14  →  ^0.12.7
 scotch-tape     0.2.0  →    0.2.1
 big-integer  >=1.1.5  →  >=1.6.26