Resolve incorrect HOME_PATH/BASE_PATH settings

JB/setup needs to account for  being falsy. Also add better usage instructions for BASE_PATH. Fixes plusjade#30

_config.yml

@@ -34,14 +34,28 @@ JB :
   version : 0.2.0
 
   # All links will be namespaced by BASE_PATH if defined.
-  # This is required for hosting GitHub Project Pages.
-  # If you are deploying this website for one of your GitHub projects
-  # you must set BASE_PATH to the name of your GitHub project.
+  # Links in your website should always be prefixed with {{BASE_PATH}}
+  # however this value will be dynamically changed depending on your deployment situation.
   #
-  # Leave this blank if you have defined a CNAME for your site (pages.github.com)
-  # NOTE: When in localhost, your site will run from root "/" regardless of BASE_PATH
+  # CNAME (http://yourcustomdomain.com)
+  #   DO NOT SET BASE_PATH 
+  #   (urls will be prefixed with "/" and work relatively)
   #
-  BASE_PATH : ""
+  # GitHub Pages (http://username.github.com)
+  #   DO NOT SET BASE_PATH 
+  #   (urls will be prefixed with "/" and work relatively)
+  #
+  # GitHub Project Pages (http://username.github.com/project-name)
+  #
+  #   A GitHub Project site exists in the `gh-pages` branch of one of your repositories.
+  #  REQUIRED! Set BASE_PATH to: http://username.github.com/project-name
+  #
+  # CAUTION:
+  #   - When in Localhost, your site will run from root "/" regardless of BASE_PATH
+  #   - Only the following values are falsy: ["", null, false]
+  #   - When setting BASE_PATH it must be a valid url.
+  #     This means always setting the protocol (http|https) or prefixing with "/"
+  BASE_PATH : false
 
   # By default, the asset_path is automatically defined relative to BASE_PATH plus the enabled theme.
   # ex: [BASE_PATH]/assets/themes/[THEME-NAME]

_includes/JB/setup

@@ -5,7 +5,7 @@
   {% if site.JB.setup.provider == "custom" %}
     {% include custom/setup %}
   {% else %}
-    {% if site.safe and site.JB.BASE_PATH %}
+    {% if site.safe and site.JB.BASE_PATH and site.JB.BASE_PATH != '' %}
       {% assign BASE_PATH = site.JB.BASE_PATH %}
       {% assign HOME_PATH = site.JB.BASE_PATH %}
     {% else %}