Update mail api to support `from_addr` parameter

Also change send_mail to an dummy function, just print out the
parameters instead of sending a real mail.
Update taskqueue's hint message to be consistent with mail's
Add _restful_mysql module and a mysql cmdline tool
Lazy check storage configuration

So this module will be importable everytime.
Commands can run in any subdirectory of the app
Add shell subcommand to saecloud
Remove stale upload-data subcommand
When deploying, cleanup the svn repo before update the cache
Add doc for storage.Error
Prefer to use 'import pylibmc as memcache' than 'import pylibmc'
Validate connection before enter the main loop
Add sae.ext.* modules
Add doc for `cloudsql.py`, `saecloud shell` etc.
About sae.ext.django.monkey
Fix sae.ext.django.storage.backend
Add docs for some django extensions
About MySQL InterfaceError (-1, 'totally whack')
Bump version