Revert "RUBY-167 Cursor#alive?"

This reverts commit 91308cdc60.
Wrong JIRA Issue

lib/mongo/cursor.rb

@@ -93,18 +93,6 @@ module Mongo
       end
     end
 
-    # Guess whether the cursor is alive on the server.
-    #
-    # Note that this method only checks whether we have
-    # a cursor id. The cursor may still have timed out
-    # on the server. This will be indicated in the next
-    # call to Cursor#next_document.
-    #
-    # @return [Boolean]
-    def alive?
-      @cursor_id && @cursor_id != 0
-    end
-
     # Get the next document specified the cursor options.
     #
     # @return [Hash, Nil] the next document or Nil if no documents remain.

test/cursor_test.rb

@@ -16,22 +16,6 @@ class CursorTest < Test::Unit::TestCase
     @@coll_full_name = "#{MONGO_TEST_DB}.test"
   end
 
-  def test_alive
-    batch = []
-    5000.times do |n|
-      batch << {:a => n}
-    end
-
-    @@coll.insert(batch)
-    cursor = @@coll.find
-    assert !cursor.alive?
-    cursor.next
-    assert cursor.alive?
-    cursor.close
-    assert !cursor.alive?
-    @@coll.remove
-  end
-
   def test_add_options
     c = @@coll.find
     c.add_option(OP_QUERY_EXHAUST)