fix a bug in `motion update' where comparing version will do unexpected behavior using the string
fix a bug in `motion update' where comparing version will do unexpected behavior using the string

"2.9" > "2.10" #=> true

So, when we released version 2.10,
Prompting message to update that may not be appeared.

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