now passing options object defined in config.json to the execFile
options parameter to fix maxBuffer issue

changed the plugin registration to a single line using a better
filename pattern
resolved merge from upstream version, changed execFile options from the \'sass\' property to sass.exec_opts in config.json to allow for other configuration later
Merge pull request #7 from Razorfish-Central/master

allow execFile() options to be configured via wintersmith config.json