Use local copy of npm.cmd

Fixes #196
Skip full URLs when normalizing CSS paths

Fixes #195
Option to generate LESS sourcemaps.
Remove old '--line-numbers' option for LESS sourcemaps generation and add 'map' extension.
Always use correct target path when generating sourcemaps.
Merge pull request #197 from SLaks/node-less-fixes

More LESS compilation fixes
Merge pull request #200 from Grepsy/master

Option to generate LESS sourcemaps.