Fix Invalid examples

1. String#encode should not fail if given an invalid code like '\x81'
This is because this problem has been resolved by ruby-ldap#41.

2. Net::LDAP#search should return a boolean if return_result is false.

Author: Tatsuya Sato

spec/unit/ber/ber_spec.rb

@@ -89,9 +89,9 @@
 				["6a31b4a12aa27a41aca9603f27dd5116"].pack("H*").to_ber_bin.should == 
 					"\x04\x10" + "j1\xB4\xA1*\xA2zA\xAC\xA9`?'\xDDQ\x16"
 			end
-      it "should fail on strings that can not be converted to UTF-8" do
+      it "should not fail on strings that can not be converted to UTF-8" do
         error = Encoding::UndefinedConversionError
-        lambda {"\x81".to_ber }.should raise_exception(error)
+        lambda {"\x81".to_ber }.should_not raise_exception(error)
       end
     end
   end

spec/unit/ldap/search_spec.rb

@@ -3,7 +3,7 @@
 describe Net::LDAP, "search method" do
   class FakeConnection
     def search(args)
-      OpenStruct.new(:result_code => 1, :message => "error")
+      OpenStruct.new(:result_code => 1, :message => "error", :success? => false)
     end
   end
 
@@ -22,7 +22,7 @@ def search(args)
   context "when :return_result => false" do
     it "should return false upon error" do
       result = @connection.search(:return_result => false)
-      result.result_code.should == 1
+      result.should be_false
     end
   end