Change behavior when no src #347
Description
Currently sassdoc executed as-is will try to read from stdin for SCSS input (that is, meant to be used like cat file | ... | sassdoc.
Though I don't expect this to be a common use and we might better default to documenting the CWD when SassDoc is executed without any src.
The - is a standard convention to mean stdin/stdout in Unix commands: http://tldp.org/LDP/abs/html/special-chars.html#DASHREF2