Merge pull request ruby-ldap#89 from sdalu/patch-1

Adding Net::LDAP::Entry#first

Author: schaary

lib/net/ldap/entry.rb

@@ -113,6 +113,14 @@ def [](name)
     @myhash[name] || []
   end
 
+  ##
+  # Read the first value for the provided attribute. The attribute name
+  # is canonicalized prior to reading. Returns nil if the attribute does 
+  # not exist.
+  def first(name)
+    self[name].first
+  end
+
   ##
   # Returns the first distinguished name (dn) of the Entry as a \String.
   def dn