Remove unused instance variable @__imported_arity

git-svn-id: https://svn.code.sf.net/p/rubycocoa/svn/trunk/src@2511 f4f36d40-9719-0410-9868-dde021a23eda
Fix error with ruby-2.0

- tc_bool.rb: require path of .bundle to relative.
- tc_nsstring.rb: add magic comment for encoding.

git-svn-id: https://svn.code.sf.net/p/rubycocoa/svn/trunk/src@2512 f4f36d40-9719-0410-9868-dde021a23eda