Fix #19 homesickrc pathname needs a to_s to eval

Also, moved the file evaluation into a new function so the script can be
ran manually which should make testing these scripts easier.

lib/homesick.rb

@@ -52,13 +52,21 @@ class Homesick < Thor
         end
       end
 
+      rc(destination)
+    end
+  end
+
+  desc 'rc CASTLE', 'Run the .homesickrc for the specified castle'
+  def rc(name = DEFAULT_CASTLE_NAME)
+    inside repos_dir do
+      destination = Pathname.new(name)
       homesickrc = destination.join('.homesickrc').expand_path
       if homesickrc.exist?
-        proceed = shell.yes?("#{uri} has a .homesickrc. Proceed with evaling it? (This could be destructive)")
+        proceed = shell.yes?("#{name} has a .homesickrc. Proceed with evaling it? (This could be destructive)")
         if proceed
           shell.say_status 'eval', homesickrc
           inside destination do
-            eval homesickrc.read, binding, homesickrc.expand_path
+            eval homesickrc.read, binding, homesickrc.expand_path.to_s
           end
         else
           shell.say_status 'eval skip', "not evaling #{homesickrc}, #{destination} may need manual configuration", :blue