Hide release tasks

before (46):
```
rake announce              # publish   # Announce your release
rake audit                 # test      # Run ZenTest against the package
rake blog:publish          #           # Updates and publishes the blog for the just-released RubyGems
rake check_extra_deps      # deps      # Install missing dependencies
rake check_manifest        # debug     # Verify the manifest
rake clean                 # clean     # Clean up all the extras
rake clobber_docs          # publish   # Remove RDoc HTML files
rake clobber_package       # package   # Remove package products
rake config_hoe            # debug     # Create a fresh ~/.hoerc file
rake dcov                  # publish   # Generate rdoc coverage report
rake debug_email           # publish   # Generate email announcement file
rake debug_gem             # debug     # Show information about the gem
rake default               # test      # Run the default task(s)
rake deps:email            # deps      # Print a contact list for gems dependent on this gem
rake deps:fetch            # deps      # Fetch all the dependent gems of this gem into tarballs
rake deps:list             # deps      # List all the dependent gems of this gem
rake diff_rubinius         #           # Diffs Rubinius HEAD with the currently checked-out copy of RubyGems
rake diff_ruby             #           # Diffs Ruby HEAD with the currently checked-out copy of RubyGems
rake docs                  # publish   # Build RDoc HTML files
rake gem                   # package   # Build the gem file rubygems-update-2.2.2.gem
rake generate_key          # signing   # Generate a key for signing your gems
rake git:newchangelog      #           # Print the current changelog
rake guides:publish        #           # Updates and publishes the guides for the just-released RubyGems
rake install_gem           # package   # Install the package as a gem
rake install_plugins       # deps      # Install missing plugins
rake install_test_deps     #           # Install gems needed to run the tests
rake multi                 # test      # Run the test suite using multiruby
rake newb                  # newb      # Install deps, generate docs, run tests/specs
rake package               # package   # Build all the packages
rake post_blog             # publish   # Post announcement to blog
rake publish_docs          # publish   # Publish RDoc to wherever you want
rake release               # package   # Package and upload; Requires VERSION=x.y.z (optional PRE=a.1)
rake release_sanity        # package   # Sanity checks for release
rake release_to_gemcutter  # gemcutter # Push gem to gemcutter
rake repackage             # package   # Force a rebuild of the package files
rake rerdoc                #           # Rebuild RDoc HTML files
rake ridocs                # publish   # Generate ri locally for testing
rake test                  # test      # Run the test suite
rake test:slow             # test      # Show bottom 25 tests wrt time
rake test_cmd              # test      # Print out the test command
rake test_deps             # test      # Show which test files fail when run alone
rake update_rubinius       #           # Updates Rubinius HEAD with the currently checked-out copy of RubyGems
rake update_ruby           #           # Updates Ruby HEAD with the currently checked-out copy of RubyGems
rake upload                #           # Upload release to rubyforge and gemcutter
rake upload_to_gemcutter   #           # Upload release to gemcutter S3
rake whitespace            #           # Cleanup trailing whitespace
```

after (29 entries):
```
rake audit             # test      # Run ZenTest against the package
rake check_extra_deps  # deps      # Install missing dependencies
rake check_manifest    # debug     # Verify the manifest
rake clean             # clean     # Clean up all the extras
rake clobber_docs      # publish   # Remove RDoc HTML files
rake clobber_package   # package   # Remove package products
rake config_hoe        # debug     # Create a fresh ~/.hoerc file
rake dcov              # publish   # Generate rdoc coverage report
rake debug_email       # publish   # Generate email announcement file
rake debug_gem         # debug     # Show information about the gem
rake default           # test      # Run the default task(s)
rake deps:email        # deps      # Print a contact list for gems dependent on this gem
rake deps:fetch        # deps      # Fetch all the dependent gems of this gem into tarballs
rake deps:list         # deps      # List all the dependent gems of this gem
rake docs              # publish   # Build RDoc HTML files
rake gem               # package   # Build the gem file rubygems-update-2.2.2.gem
rake git:newchangelog  #           # Print the current changelog
rake install_gem       # package   # Install the package as a gem
rake install_plugins   # deps      # Install missing plugins
rake multi             # test      # Run the test suite using multiruby
rake newb              # newb      # Install deps, generate docs, run tests/specs
rake package           # package   # Build all the packages
rake repackage         # package   # Force a rebuild of the package files
rake rerdoc            #           # Rebuild RDoc HTML files
rake ridocs            # publish   # Generate ri locally for testing
rake test              # test      # Run the test suite
rake test:slow         # test      # Show bottom 25 tests wrt time
rake test_cmd          # test      # Print out the test command
rake test_deps         # test      # Show which test files fail when run alone
```