Adds a helper method to gulpfile.js so that we can easily switch between
*nix and Windows (using batch) formats for spawned processes.
specify older version of gifsicle builds on debian without error
fixed issue with pngcrush on debian 7 x64 that prevented gulp from continuing after calling jekyll build
Merge pull request #50 from kylegordy/master

make footer links relative to match PR #49
Merge pull request #48 from chadev/debian-fix

Debian fix
Merge pull request #47 from StrangeWill/master

Gulp Configuration For Windows