fix a bug where `motion update' causes an error when display the changelog on OSX 10.9
fix a bug where `motion update' causes an error when display the changelog on OSX 10.9

https://groups.google.com/forum/?fromgroups#!topic/rubymotion/HXO7wRn1Cuw

`motion' command uses system bundled Ruby.
If run `motion' command without local environment variable (ex LC_ALL or LANG),
Ruby 2.0 which is bundled in 10.9 might cause encoding error.

jjaffeux/RubyMotion,beni55/RubyMotion,hboon/RubyMotion,jjaffeux/RubyMotion,hboon/RubyMotion,incbee/RubyMotion,incbee/RubyMotion,HipByte/RubyMotion,katsuyoshi/RubyMotion,jjaffeux/RubyMotion,incbee/RubyMotion,beni55/RubyMotion,katsuyoshi/RubyMotion,beni55/RubyMotion,HipByte/RubyMotion,incbee/RubyMotion,jjaffeux/RubyMotion,beni55/RubyMotion,hboon/RubyMotion,HipByte/RubyMotion,katsuyoshi/RubyMotion,katsuyoshi/RubyMotion