- Allow database shard shared nothing architeture with resharding
- Configuration template in domains/default/shard.inc.php.dist
- Frontend_Cli class to perform Shard configurations and operations
- Sharding is added in Tinebase as a Plugin
- Manager class is a controller that coordinates everything
- ModOfDivision class is a Strategy to associate Shard Keys with Virtual Shards
- Loginname class is a Strategy to allow user email address to be Shard Key
- Filesystem classes are backends that allow all Shard control informations
  to be persisted in a filesystem folder (that must be shared between frontends)
- Connectionconfig subpackage allows to persist DB Connection Configs
- Association_Virtualshard_Connectionconfigkey subpackage allows to persist
  associations between Virtual Shards and DB Connection Configs
- Persist Resharding state transitions using
  Resharding_Association_Shardkey_Connectionconfigkey subpackage
  and Resharding_Flag subpackage
- Perform Resharding operations that copy tables contents between DBs
  using Redistributer subpackage
- It requires multidomain enabled to work
- Allow configuration of Shard for ActiveSync separated backend
- Look at Tinebase/Shard/readme.txt

Change-Id: I626ebe2773e440e20678fcb712b2b067228bc83c