widening supported net-ldap versions. fixes cschiewek#103

i wish i could have done a hybrid ~> 0.2.2 or ~> 0.3, but this shouldn't
matter. This exposes some chance that devise_ldap_authenticatable is run
against net-ldap 0.2.0 or 0.2.1, that exposure is small. We still want
to support devs wanting to use 0.2, but now we'll be able to tell devs
running into the encoding issue to just explicitly update net-ldap.

Author: stevenyxu

devise_ldap_authenticatable.gemspec

@@ -18,7 +18,7 @@ Gem::Specification.new do |s|
   s.require_paths = ["lib"]
 
   s.add_dependency('devise', '~> 2.0')
-  s.add_dependency('net-ldap', '~> 0.2.2')
+  s.add_dependency('net-ldap', '~> 0.2')
 
   s.add_development_dependency('rake', '>= 0.9')
   s.add_development_dependency('rdoc', '>= 3')