adding a default.json file as base for default config settings

e.g. the standard sass dialect lives in here and other stuff like stylesheet root file name and all necessary configuration options necessary for future use.
removing cli require statement from standard toppings lib

it is already defined inside of the bin file and makes irb unusable otherwise
adding a config class for toppings
adding options attribute as container for given configuration options
fixed blobbed require statements for foreign folders, that include the toppings gem
cleaned up gemspec a little
added gem_root helper to toppings gem
formatting
added a comment for ordering of require statements here
removed unnecessary require statement